I dated my boyfriend before going Greek. He is out of college already, a GDI, and lives a couple hours away, but we've done well with me going Greek... in fact, it's better this way because I am able to keep busy at school and have a life of my own! He encouraged me to rush and is usually pretty cool with my schedule of commitments.
The two occasions that get him slightly grumpy, RARELY:
1. Recruitment (because I disappear for two whole weeks!!)
2. As previously mentioned, social events centered around meeting fraternity men
Honestly, it depends on the guy! Some will be cool with it... others will give you hell for it... some will have a lukewarm reaction. Personally, it's a huge turn-off for me if a guy doesn't admire me for being an independent and productive individual. Guess I have it pretty good!