I met this guy at my dad's birthday party in May, he's the son of one of my dad's friends. I saw him stare over at me quite a lot at first (I'd never met him before) and towards the end of the night he was talking to my dad while I was nearby so I struck up conversation with him, then he spent the rest of the night talking to me, came over to sit next to me, he stood on my foot at one point and was so apologetic it was adorable! Anyway so as I was leaving he invited me out for a drink (the party ended ridiculously early!) but I had to go with my parents cause I was staying with them and they live in the middle of nowhere! So anyway, his mother was exhibiting work at some gallery in June and myself and family were invited, so I told him I'd see him there and he looked pretty happy.
So the day came of the exhibition, as soon as I saw him he smiled (slightly nervously) over at me, I smiled back but looked away quickly (I'm the sort who gets so embarrassed that the person I like will realise just how much I like them!) Well I did end up talking to him quite a lot but as a way to calm the nerves I ended up drinking too much and probably (in my opinion) spoke a load of trash but I did notice him staring across the room at me a lot and smiling when I caught his gaze. At the end he asked me out again for a drink afterwards and this time I persuaded my parents to stay too so I could get a lift home! His face lit up when I said that I'd love too! While all his friends were there in the bar he talked only to me, pulled his chair over to me, and asked me loads about myself, told me about himself etc. He told me to add him on bebo as I left (unfortunately there was no kissing as both our parents were right there!  ), he shook my hand and touched my arm as I left too. So I added him, we talked loads, then he started taking longer to reply, until he didn't reply at all. Then he dropped me a comment, I replied, he replied, I replied and then he just didn't reply at all. he would be active on bebo and talk to other people but not reply to me for ages. I hoped he was just waiting til he had time to think of what to write - his answers were always really long and enthusiastic. I haven't spoken to him in about 3 weeks now. I don't want to come across as too pushy as I'm always the last one to comment and he just doesn't reply so it feels like the balls in his court. I dunno if its cause my comments aren't exactly answerable (I have noticed that the last comment I wrote couldn't really be answered, it's a bit of a hint for him to ask me out, but a bit too subtle I suppose! :S ) He seemed to really like me when we met, but now I'm not so sure cause he just doesn't seem to talk. He's a really sweet guy and from what I've gathered he's been single for years, i dunno if he's shy, scared of rejection or just not interested, what do you think?
Sorry for the length!

Thanks for the advice, my friends seem to think that I have a chance with him but I'm not so sure and I still haven't sent him a message, I know it's stupid but I just haven't plucked up the courage. I will try though!

Well, I sent him a message, no reply yet... I should probably just move on.