We all get along generally well on a day-to-day basis. I have friends in both the other sororities and in the fraternities. In general, each sorority gets along well with all the fraternities (i.e. will have mixers with any of them). I think the boys have their preferences, however.
BUT, when it comes to things like Greek Week, Derby Days, and recruitment, we get really competitive with the other sororities. It's hard to maintain unity when you're all after the same prize, so to speak. Outside of "competitions" like that, we're generally peaceful.