Possible psychological disorder?

Hi all! I'm new to the forum, and I know that someone can't be diagnosed without professional psychological help. I just needed to open up and reach out to someone, and I my friends and family most likely will not take this seriously or will just write this person off as a jerk with issues.

There's this guy I've know for a little over a year. He found me through Facebook, we messaged a couple of times (we had mutual friends), and eventually he asked me out. He came on pretty strongly, and I was worried about clingy-ness issues, but he seemed like a nice person. After a few dates (and a pretty intense make-out session), I told him that maybe we should get to know each other more and take things slowly. He ignored me for about a month. Repeated texts from me received no response at all.

Then, out of nowhere, he texts me again, asking for another chance, saying that he doesn't just want to be friends, that he wanted something serious. I asked him about the silent treatment he gave me, and he said that he thought it was weird that I was unexperienced (sexually) when he was so experienced. I gave him a second chance, and after about two months, I was spending time at his place (no sex, however--just making out), but he kept on putting off making the relationship official (when he was so eager to be in one before), saying things like he wanted to wait until he finished moving, the timing wasn't right, and he really really wanted to have sex with me first. So I wrote him a message about my feelings toward him, he said we should spend some time apart.

I've lost track of how many times he's given me the silent treatment. They would last anywhere from a week to a little more than a month. Through texts, it was nearly impossible to get him to talk about anything besides sex.

On Facebook, he's been friends with a whole bunch of girls (who would comment on his wall/photos) who aren't his friends anymore. He's still constantly unfriending girls and friending new ones. I know that he's met with some of them.

During the last month, we've started hanging out again, coming close to going all the way (i.e. sex) a couple of times, but he said he'd take it slow.

He doesn't have a high opinion about almost any of his friends (or their significant others) and more than once has told me that some of his female friends stopped talking to him because they found boyfriends who he felt they were too good for. He also seems to have no trouble just cutting people out of his life, doing it to both friends and immediate family members. He keeps a stock of weapons (guns, swords, bows) in different spots in his bedroom and sometimes even sleeps with a gun cocked under his pillow at nights, just in case someone comes into his place. He doesn't talk about girls--and most people in general--with respect, but he has impeccable manners (holding the door, walking me to my car, making sure I'm comfortable).

Since last week, he's been ignoring me, texts, and calls. I stopped by his place today, and he would not answer the door or anything, even though he was clearly home. I do have to say we had been making plans to go to the movies, and I asked him when he would be free. He always has his phone on him and will usually return texts within minutes, but after no response for half a day, I texted him again. No response, so I called him, which he ignored. After I texted him two more times, he snapped at me and texted that he was busy. Nothing from him since then.

I do really care about him, and this has gotten to the point where I'm really worried about him, as well. Does this sound like someone who could have a psychological disorder? Does anyone have tips on how I can deal with this? I'm planning on trying to see him again in three days, but I don't have a lot of hope. I have a feeling he'll see me, turn right around, and run.

Does anyone have any idea? I'm really worried about him and would like to make everything alright between us, but I don't know how to get through.