Depends how you define coitus I guess. I'd be perfectly happy in a relationship with someone who was okay doing other sexual things but not conventional penis-in-vagina sex.
I think my main problem would probably be ideological - I have never understood how God could take umbrage at people having consensual, happy, safe sex before marriage - it just seems so harmless. As I've said elsewhere, I consider a thing sinful if it causes harm to a sentient creature, and there just doesn't seem to be a victim here. I'd be more put off by the fact that the other person doesn't seem to have examined and questioned their own beliefs, than that they weren't comfortable with sex.