He was asking for "more girls" so of course he wasn't referring to a serious relationship. His question actually means: "will i get to have sex with a number of girls if i join a fraternity?"
The answer (in my opinion) is; if you were having sex before joining a fraternity you might keep having sex but if you were a virgin before joining a fraternity that might not change. I mean a girl wouldn't sleep with me just because i'm a member of a fraternity.
