Man's opinion

I'm always puzzled when guys say they cannot understand women, that we are too complicated. But seriously guys, don't even get me started on which gender is more complicated and bizarre. I happened to be in a strange situation recently so I finally had to engage some innocent bystanders and practically terrorize them until they shared their honest opinion with me. By innocent bystanders I mean two male friends of mine who I thought should be able to provide me with some insight as to this issue. I have already formed my own opinion before I talked to any of them, but wasn't sure it was the correct one, since male and female brains work in opposite directions it seems. Then I talked to each of them separately to get some male perspective. The reason I asked two of them is to avoid any possibility of bias which could have occurred had I asked only one guy. Now by having my thoughts and their respective ideas I was hoping I was going to be able to get to some conclusion that made sense to me. Well, turns out, even after they shared some information with me and I slept on it, things don't make much more sense than they did yesterday afternoon. Actually, they sort of do, but now I am even more perplexed about the entire situation than I was before. But enough about what I think and back to the issue, I guess.
As you probably have guessed, it is about a guy. I met him a while ago, online. As we started talking, we inevitably got to the question of what we are both expecting from each other. Turns out we were both looking for something casual at the time (now I don't know his reasons but I have just got out of a weird relationship and wasn't about to jump into another one). I do not recall who mentioned the casual thing first, and as one of my friends pointed out, it is an important aspect that can impact the way he thinks. Too bad I didn't keep notes. We finally met sometime last June and spent one night together. Afterwards, we kept talking online quite often, but our respective schedules kept us from seeing each other again even though both he and I attempted to meet up numerous times. Unfortunately that never happened. As of about two-three months ago though he started asking me if I met someone else or if I've slept with someone else since we hooked up. Going back to our initial conversation, we made an agreement to tell each other if we've slept with someone else while we were seeing each other (I guess here goes a trust issue). So, every time he'd ask me if I slept with someone else, I'd say no (which is the truth, since I haven't been with anyone since he started asking me that question). After my answer, he'd just move on to another topic in our conversation. This fact always left me wondering why he would ask me this question, because it sounded like he was asking me if I was with someone else while I was with him (let me remind you, we agreed it was OK to see other people as long as the other person knows about it). So yesterday, after another round of interrogation from him, I finally decided to get some man opinion about this. I figured a guy would know better why another guy is acting one way or another. So the question I asked both guys was:
"Why does he ask me if I hooked up with anyone anytime we talk online?"
I gave them some background so they were familiar with the situation.
Here are their response (my notes in parenthesis). By the way, they know I will be referring to them here and they don't mind.
The first guy I asked:
"Because he is curious and because he wants some repeat performance. (what does one have to do with another?) If you were having fun with someone else then maybe you wouldn't be as receptive to having fun with him too (once again, those two things are not connected since we agreed we are free to see whoever we like). You are a girl who could get with a majority of single men when you go out so he is just scared that a) you find someone you like or b) find someone so good that he won't be able to compete with him when he gets a chance. Did you hooked up with him ever since (no, it was that only time). Was it good for him and you? (well, he wouldn't stop talking about it for about two weeks after it happened just having re-runs in his head, so does that mean he liked it?). Obviously then it was an experience for him and he had a very good night so now he may be wanting it to happen again on a frequent basis, so if you start seeing someone else it lessens his chances ( I still don't get how having someone else for one night - because that's what he implies when he asks me the question - can lessen his chance). It may not but he may think that."
Alright, I mean I see his point but it still hasn't made things any clearer. Except the fact that he wants to meet up again which I already knew cause he tells me that when we talk anyway.
The second guy (the reason I asked this guy was because he has a tendency to be blunt no matter how bad his response may be. I appreciate it because girls have a tendency to sugar-coat things to spare your feelings, but this guy is basically telling me things as they are according to his perspective, of course):
"Men feel possessive of anyone they have sex with. Some more then others. Some act on their feelings some don't (that's a general sweeping statement). He might feel possessive without acting on it. Most men don't like to share their women. (at this point I told him about our agreement to see other people while informing each other of it. I also told him that I answered his question and that I was honest with him. I told him that we haven't seen each other since so it was weird he kept asking the same thing over and over). I think he may want to date you at this point, and date you exclusively (why would you think that). Sex creates an emotional bond and separation creates desire (at this point things get pretty heated up, so he just calls me instead). When you first started seeing each other, you made an agreement it was going to be a casual thing. Now he has changed his mind, but he can't change his word because men don't do that (at least decent ones). He probably realized he wants something more but cannot say it because it would go against what you agreed on. Do you want to date him? (I think so). At this point it is up to you then to casually bring it up and maybe give him a hint. If he takes the bait, he'll continue the conversation you started and will tell you what he wants. If he was the one who first mentioned the casual thing, then just casually bring it up and see what happens from there. If you were the one who said that, then it is entirely up to you to start this conversation. If you said it first, he would never talk about being exclusive first because he thinks it is not what you want (damn, it's like saying, you made your bed, you have to lie in it now. I wish I remembered who brought it up first - for some reason I think it was me since more likely than not he asked me what I am looking for, and not the opposite. Mental note: I should definitely start keeping notes). You have to find a way to start this conversation (easy for you to say. Once we kick off the talk, I can take it from there, but I have no idea how to start)."
We talked for a little while more trying to come up with different ways to have this conversation and so far have come up with two scenarios: either bring it up after sex or give an example of a third party changing their mind on their word (my friend thinks it might prompt the guy to speak up if he knows I think it's OK when people change their initial intentions). I like the first one more since it has a double meaning and if he doesn't follow through, I'd be able to brush it off as a joke. If he does though, then it would be a kick-start for a conversation.
I'll leave my thoughts to myself right now, cause I am not sure yet I digested all this information and know exactly what to do. I'll let you know when I decide.