I'll try to summarise. I met a guy through a shared hobby some years ago and was immediately attracted to him. He seemed to be single but he never asked me out, despite being (confirmed by everyone who knew either him or me) being flirtatious and clearly liking me. He seemed to get jealous when he saw me with another guy.
Eventually, he did ask me out, only to change his mind (by text). We continued with the hobby, and to see each other through that a couple of times per week. I remained attracted to him but always had some sort of "feeling" about him that made me nervous. He seemed to act strangely at times, at other times was really frieendly/flirtatious, at other times would completely blanked me. He then asked me out properly. I said no, because I was bothered by his odd behaviour. It then turned out that he had a long term girlfriend - a mutual male friend told me he had mentioned bringing her to his party and he contacted me because he thought there was something between us and he was really surprised he had never mentioned this girlfriend. Apparently, it was long distance.
About a year later, really curious, I contacted him, he asked me out and assuming that he was now single, we went on a date. I assumed the girlfriend was no more. Seemed to be getting on really well, at the end of it, I tried to hold his hand and he said "Sorry, but I'm not really into dating or stuff like that". I asked him about the gf and he said they had split up a while ago. I was mortified and we parted. Later on, I wondered if he had just been looking for a one night hook up.
Still the flirting and attraction through the mutual hobby continued, I contacted him about a year later to meet up for a coffee, we then saw each other a few more times on dates, he invited me round for dinner, we did the deed, we saw each other a few more times, including dates not just sex, everything going great, getting on really well, no arguments, and then he dumped me out of the blue by text. I more or less forced him to meet up for a coffee to do it in person and he was kind of confident and a bit cocky, different from what he was when we had been dating. He was saying all sorts of weird stuff about how he "didn't do relationships" and was unreliable, and not to bother with him, etc.. At this point I should say that he comes across as the most reliable man around, very quiet, a little nerdy, somewhat shy. Always treats me well, not extravagant but not mean either. We just get on well.
A few weeks later, a mutual female friend told me she had gone on a couple of dates with him after matching online around the time he dumped me, she had no reason to believe he wasn't single, he never mentioned me and he dumped her. I don't know if they slept together, I didn't want to hear the answer as it was still quite raw. She was quite mortified.
A couple of years later, we bump into each other, went for a coffee, he invited me round for dinner, I stayed the night and we have now been dating for the past few months, but I still have doubts. I am really attracted to this man and we get on great, but I have these nagging doubts about him and the way he has behaved, nothing I can put my finger on but....but then again, when I am with him, everything is perfect and I've never been happier. Its possible to say that now he is a little older and has been given a nice flat by his parents - he doesn't work full time but does a few hours yoga teaching and fitness training), he feels more able to commit to a relationship.
Again, theres nothing I can put my finger on and he really is behaving like the ideal boyfriend, very considerate, kind and passionate in the bedroom. But I can feel myself disappearing down a rabbit hole and becoming more withdrawn - he drops little things into conversation about how he doesn't like to socialise and "doesn't like people" and we end up more and more just staying in and watching Netflix. He's kind of all consuming but I feel I can't relax because he will let me down again. If I attempt to talk about it with him, he is niceness personified and extremely apologetic, saying he was younger then. But he then moves the conversation quickly on.
Its just very hard to get a handle on him. What do others thing? Why do I have these feelings? I haven't been insecure in relationships before (only had 2 serious ones other than this!). Basically, I'm wondering if I should continue with this relationship or if he is going to let me down again.