If you like Looper "ok" then you will probably love Belle and Sebastian because they are much better.
Have you also considered possibly just not listening to music together? I mean, I don't know, what's the big deal? Can't you like, talk, or watch movies, or just not care about music when you're together? If you live together, can't you use headphones? If you guys really like each other, can't you "tolerate" anything the other wants to listen to as long as you, I don't know, take turns or whatever? I hate to get all serious but if this is in any way a big deal then it does not bode well for your future relationship.