I’m so insecure. I don’t know why he likes me

Idk why recently I’ve been feeling uglier than usual and more insecure that it’s been making me think why he has feelings for me? Or why he likes me? There are so many pretty girls out there but I feel like he got bad luck with me. The worst part is that this summer will be our 3 years and I feel sorry that I look like the way I do??.....he’s def more attractive than I am. Btw I’m 21 and I really want to stop thinking like this it’s tiring