In case you don't know this scene, this girl is categorized as a solid 10 in terms of attractiveness and the guy she is with is insecure and thinks he is a 5 at most and thinks she's too good for him.
I know for me, I often think that way. Even now I'm really into this one girl who I think is very cool but also very very cute and attractive and I'm like there's no way she'd be into me. Look at the options she has with other hotter dudes (which does not equate to being a douchebag) than me.
Most Helpful Girl
It's not all about physical appearance, she might click with you and have a deeper connection which has a lot more potential as opposed to the superficial attraction. Don't put yourself down so much, have some self confidence and go get that girl. You might not think you're a ten but she might... you'll never know unless you try