Prom Proposal Help! Which song is best to play for a girl?

I'm doing a prom proposal for a girl. I'm going to be playing an acoustic guitar and singing. I need song suggestions. I was going to do a huge thing but I've decided to dumb it down to make it simple. I can't sing that well and it's my first performance. I'm not that nervous but I won't mess up due to sweaty hands or something like that. Thank you for your time and suggestions. via http://wapmaxi.com