What can I do with these characters?

I'm writing a story about a med school student who meets and falls in love with an NFL quarterback. I need there to be some sort of fight, but I don't really know what they should fight about. She's fiesty and a bit shy and doesn't like being in the spotlight- paparazzi follow her because she's his girlfriend. He is very down to earth and religious. I don't want cheating or anything like that, so what can these two fight about? It could be anything I just need suggestions... Thank you so so much!