Guy's Behavior

How to tell if a guy isn't interested anymore?

So I've been dating a guy for almost 3 weeks now (not exclusive) and I don't know if it's just a coincidence that he's doing this and it means nothing or if he is actually not interested anymore. I hadn't seen him since Tuesday. Because Wednesday I was sick and then yesterday he decided he wanted to play Halo and there not be any distractions, which is cool by me. So I told him maybe I could see him on Friday, then he was like, maybe, if you're not sick anymore. Then like a minute later he was like, oh wait, you might not get to come over, because I might have company. I was like, oh? He mentioned that his best friend might be coming from St. Louis and he hasn't seen him in like a year, so they have to hang. Thing is, my bday (today) is the same day me and him were going to do something; same day as his friend being in town. We never set anything in stone, but we said we'd probably do something day of or the next day (and I'm going to a concert day after my bday). So I told him I thought me and him were going to do something. he was like, I thought I said something to you. I was like, no. He hasn't been acting strange the past couple days prior or anything. At least I don't think he has or anything. He im'ed me the day I was sick and told me to feel better and all. I would think if he wasn't interested, he'd avoid me altogether, right? I briefly talked to him Wednesday on AIM when he got off work, and then he said he was going skating, and he im'ed me after he got off work. I can't imagine so much would had changed within a day.

Although I did tell him I wouldn't get to see him til Sunday and he was like, aww, it's okay. I don't know if I'm analyzing too much, but it didn't seem like he was that concerned, then again. he did tell me he has trouble reciprocating his feelings and stuff.

Am I thinking too much into this? Does it sound like I have anything to worry about? Is there anything I can do to see how he does truly feel about me? We told each other on a few occasions we liked each other, so I can't imagine it would had changed that dramatically or anything. I thought about just kind of denying doing something with him over the next couple days and see what he does, if he doesn't seem to care or if he does care. Am I just being paranoid and everything is really okay?
How to tell if a guy isn't interested anymore?
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