I think i'm in a bit of a conundrum

My reputation is not that great with people that know me. Pretty sure they view as a weird guy or something along those lines. Anyway i feel as though it would be impossible for me to seduce the girls that i'm into, girls in my classes, girls that i sit near and so on. When i do talk to them or get near them i begin to feel incredibly sexually frustrated. The only thing i want to do when i see them or get near them is pin them down and have my piece, does that make sense?

Its very annoying because i feel as though when i get too caught up in thinking about sex i'm missing crucial points about how i'm acting and parts of the game i need to be focusing on. And i feel as though that because of my reputation it would be impossible for me to get with any of these girls that i like, currently i'm not in a position to go out and have a night life, i've entered hell month essentially. Please let me know if you have any solutions or ideas on what i could do.

also as a little side note, that doesn't have to be answered, how can i get with a girl who has a boyfriend of 6 months? I know what you might be thinking 'she's taken, don't bother' but i really want her, and i've wanted her since before seduction. If theres anything i've ever wanted so much it would be her, second comes perfect seduction.

Please help me!