Why do i keep bumping into the guy i like after he gets a girlfriend?

i was seeing this guy for 5 months, we got really close. He asked me out and i said no because i wanted more time to think about it. only a few weeks ago i find out hes going out with a girl now but ever since i keep bumping into constantly when im out, for example i was going for a run and i had this feeling i was going to bump into him. As i was walking home i had my headphones in and i was thinking about him then i looked to my left and miraculously he was walking next to me, i thought i was going insane but he truly was their and we started talking. i dont believe in fate or anything like that and seeing as he has a girlfriend and i know i dont have any chance anymore but why do i keep bumping into him ever since i know i cant have him, its freaking me out thanks