A teacher and a student, two opposite cultures and a self diagnosis. [help]

I mostly lurk on here and enjoy the posts where people are asking for help and advice. Everyone seems to be so helpful and kind. So, I've decided to share my situation.I live in Japan with plenty of free time which makes this situation slightly worse because I get to spend a lot of time thinking about it. I'm a teacher and I mainly teach English and I work for a school that deals one on one with adults. I never really expected to meet anyone in this type of situation but it ended up happening very organically.I met him around this time last year, both in our twenties but he is a few years younger than I am. He's Japanese and from far into the countryside so not only is he shy, which is typical among many people here, but he is -very- shy which I chalked up to him not being a city boy. Anyway, 6-7 months went by with us having normal classes and just getting to know each other. Nothing happened. No flirting. Kept it to the books.Eventually, he found out I was gay through our conversations and he told me about a bar he went to where the bartender was transgender. He had interest in the community which I thought was cool. He would go to this bar alone, he told me, and just hang out. He invited me and wanted me to go with him to meet her, so we end up going out one night. We had a few lunches together around the school up until this point but this was the first time we were going out like that. He would still be very shy with me and we would actually stand out which made him feel like people stared at us. I am tall, and he is even taller than me (6'2~187cm) which is pretty rare here. Still, he said he would enjoy time with me even if we didn't talk a lot. One thing he did do rather frequently though, was tell me that he was "strange" and not good with people and didn't have many friends. It was contrary to my original expectations because he is tall, pretty handsome, athletic (basketball), intelligent and pretty kind. We also had many mutual interests, we are both into true crime stories and the psychology of serial killers and this kind of thing, so I knew that for us at least it was easy to get on. But still, he'd repeat that he was pretty strange socially a lot -- almost like it was a warning. This is important later.Fast forward, we start going out more frequently all through the fall. Bars, restaurants, parks and even the zoo. I thought he was straight for the longest time but he finally told me one night he felt like he was bisexual and attracted to men. I didn't think anything of the confession. We end up seeing each other more cause he started working nights as a bartender at a bar near my house. Then one of these nights after work, we end up telling each other about our feelings.So during this entire time he would message me everyday with pretty cute messages via an SMS app on the phone, he would compliment me semi-often and he made 90% of the plans to go out himself. He'd ask me when I was free and secure the date. For being a shy boy, he would be pretty unpredictable for me. Soon after our confessions he asked me out to be his boyfriend -- which was also a surprise, because I'd also be his first boyfriend. Of course, I said yes.So the time leading up to it and the beginning of the relationship was really great. We had Thanksgiving with my friends here and I introduced him as my boyfriend, I'd meet him to give him lunches I made and it was really cute. I started leaning into it and wanted to see him pretty often, like at least every week (which I didn't think was too much) but soon things began to change.He started to message me less. He stopped making plans to hang out with me. He'd be dodgy with his answers on the phone. It almost seemed like he was avoiding me after a month of dating. It was really weird for me and I probably came on strong now during this time in retrospect, cause I was frequently trying to make plans and talk to him which he'd reject. We went a few weeks before we met up again and he'd refuse to speak on the phone. We'd exchange messages which became very long especially on my part cause I was trying to figure out what was going on and let him know how I felt. When I finally saw him again he seemed very warm and happy to see me (unlike the cold distant person on the phone) and said he told me this is what he meant when he said he was weird, that he had a "mental issue" and that nothing has been my fault and that I shouldn't apologize. He said he wanted to take things easy and slow and "act like friends, for now" and kind of revert back again to not being as super cozy together. Of course this was very hard for me to hear, and I thought the gay thing might have scared him, but he claimed this would happen with a girl too -- that it didn't matter.So time went by, January now came and went. We met up for his birthday where I gave him gifts and he seemed burdened by it and taken aback. He was very distant the entire time and continued to barely message me. (If I don't first, he probably won't now)Anyway -- because I'm really into psychology and I've listened to his warnings more clearly now I looked into things. After speaking to my friend who is a therapist we've concluded that we're -pretty- sure that he might have Schizoid personality disorder. It all fits well and he actually fits all nine criteria. I have a feeling he might have even researched this and might even know this himself but of course I have not brought it up. Knowing this makes me feel better but at the same time doesn't because I do have pretty strong feelings for him. Basically, Schizoids don't understand "the point" of human relationships and can recognize love and feelings but it is hard for them to feel it or show it. Still, it is possible if done organically but they never really change. They kind of just adapt to the person but the partner should never expect to get love shown to them the way other people would. They are also not very interested in sex and don't really get lonely. He has mentioned or I've experienced a lot of these things and he's told me how difficult it is for him to text message people. It does feel like it now, especially, that he has a hard time. However, when we first started as a couple and the time before that he was very different with me so the sudden change hit me pretty hard. Thus my pretty emotional behavior after -- which is a big turn off to Schizoids. It's obviously not good to self diagnosis yourself or anyone but I'd place money on it at this point.Anyway, I'm not sure what to do now. I'm not sure if I should keep trying to keep contact with him or just distance myself and let it rock. He's told me I'm the closest person to him in his life, so I have this advantage, but he doesn't seem like the type of person that even needs anyone to "talk" to about anything. It hurts me to try and move on because I really, really like this guy, but I'm feeling pretty hopeless about it moving forward right now.Has anyone ever dealt with or know anything about Schizoid (I also don't mean any disrespect about anyway I described it. Pretty sure we all have traits of disorders, anyway, but to different levels) Any experience dating someone from a very different culture? What would ya'll do now? Should I just show up at his bar after work and surprise him to hang out with him? I've done it before when things were still happy and he was very happy to see me, but I wonder if it'd a good idea now....TLDR TLDR TLDR TLDR: (and if you read all that, phew, thanks) I'm American dating a Japanese boy, both in our twenties, at first things were great and when we became official he got really distant and cold with me. Would always warn me something was "wrong" with him, and after some research pretty sure he might have Schizoid personality disorder. Unsure of what to do next as our relationship is kind of at a standstill right now.