making friends in frats

I think my sorority is really great, and I love going to sisterhood events, study hours, philanthropy stuff etc. But I don't drink or go out that much to pit nights/bims on wednesdays because I have a really crazy workload this semester. I have gone to a few exchanges, but each time I've talked to a frat guy who I think is cool and I would want to be friends with, as soon as they figure out I'm not down to hook up with them they're no longer interested in hanging out/talking. I really do want to have a fun year and make friends and meet people, guy friends included! But I don't know how to do that without sending the wrong message, because "hey you're cool, let's hang out" to a guy always seems to get misinterpreted. Am I doing something wrong or giving off the wrong vibe?