The note from which a chord is built - Emery
With Me - Sum41
If you're gone - Matchbox20
Bent - Matchbox20
Parabola - Tool (maybe)
Motorcycle drive by - third eye blind
A few ideas. A couple are pretty obvious so you've probably already decided against them. The third eye blind song would be good if they weren't together anymore. I've always wanted to use that song but I've never been able to make it work.
Something like a friendship song...Maybe ...'Saving Jane - Girl Next Door' if it's between two friends...And if it's gonna be as a relationship...
Amy Diamond - My name is love xD
The Veronicas - Untouched
Evanescence - Taking over me
Good Charlotte - Riot girl
And...I can't remember anything else xP Hope I helped yah ^_^