How to move on from a missed opportunity with a girl?

r/

This kind of post has been made here in some shape or form too many times to count, but here goes anyway,

I, 27(M), am finding it pretty tough to get over a missed opportunity with a girl. Long story short, I ignored all the signs from a genuinely nice girl that I met through friends, who made it as obvious as she could that she was interested in me, to instead try chase the high of getting with ‘more attractive’ women.

She’s since got with another guy I know, and they’re together a couple of months. She’s moving country, but they’re staying together while she’s away.

I went to her going away party a few weekends ago, and since then I can’t get my head around the fact that I didn’t even think to take an opportunity with a genuinely lovely, smart girl.

All for the sake of a bit of tail and the ‘potential’ of someone ‘better looking’.

Guys out there who’ve experienced similar, what helped get you over this?