Why has he kept me on facebook after this?

i met him 2 yrs ago but we lost contact texting as i was not over another guy. he randomly added me on facebook few months back and asked me out but i couldnt then as in wasnt back from uni. anyway 4 months later we went out. amazing date wanted t se me again n did lots of cute things wanted to know abou tmy family etc. when i thanked him for nice time by text he said he ws looking forward to next one now! few days later we were in the middle of arranging second date he asked what i wanted to do but i heard nothing from him. its not like he ddnt wnt to. anyway hes in his final yr uni so i know he has alot on his mind /to do. anyway i think as we were making arrangements to see each other at the same time an argument or something must have happened with his ex gf frm uni as they deleted frienship then re added on fb. i text him and he ddnt reply so i was a bit angry but we were in the same club a few weeks later as his team and another team wich happens to be one his x is on had an awards night. he didnt speak to me (don’t know if he saw me) but he kinda....just looked at his phone a night really.....he still has me on fb though...why has he kept me? i know people say it's not a big deal but this is abit different as he obviosly likd me but something argumentative must have happened with her and him (it’s just an odd coincidence it was just after he saw me even though he’d asked me out 4 monthspreviously). I’m just worried thatm i f they hang out they’l get back together or something. His friends have commentd his page with things to suggest he hasn’t contacted anyone for a while but I another one has mentioned something about the 2 on each others pages i don’t know if he’s seen her. and also i'm not saying they cant spend time together even if they are friends. i’m 20 hes 24