Do they need to be pop songs? Or could you do some classic motown? Or are you talking about actual classical pieces to be sung during the ceremony?
It depends where and when you are singing them. If it's during the ceremony, you need details from her on length, style, etc. If it's during the reception, does she want you to get the crowd going or is this for her first dance or during dinner instead of a speech? Also consider, does she have a theme or a story that could be expressed in the song, or is the general theme of love good enough?
Get more details - it will really help you choose the right thing.
Also, what kind of voice do you have? What are you most comfortable singing?
If you can provide some of the above info, I can definitely be of more help!
And congratulations, by the way! Even if it makes you nervous, it's an honour to have been asked!
