Okay, confession time. There were 2 PNMs at my school who dropped out of rush, and I'm convinced it was because of something stooopid that some of my sisters and I did.
It was my sophomore year, my first time on the other side (in my defense), and it was my local sorority's first time participating in FR (in our defense).
XYZ fraternity had offered us an open invitation to come to dinner anytime during rush week; a couple of sisters were dating XYZs, and of course the brothers knew it's a good thing to fill your house with attractive girls during rush.
During round 1 of FR, we met two very sweet PNMs, I'll call them Buffy and Willow. They were a "package deal". They were both invited to return for round 2.
After round 1 was over, we turned in our invitation list, cleaned up, set up for round 2, and then realized it was dinnertime. So a group of us decided to take XYZ up on their dinner invitation. We knew there might be PNMs there, and we knew we couldn't talk to them, but we went over to XYZ anyway.
Naturally, who should show up but Buffy and Willow.
At the time, we had extremely strict silence rules. We weren't allowed to talk to PNMs
at all outside rush parties - even to explain to them that we couldn't talk to them.
So we kept having to say to the XYZs things like, "Bob, would you do me a favor? Remind Buffy and Willow that we're not trying to be rude, but we aren't allowed to talk to them outside rush parties."
We should have left... actually, we shouldn't have gone to XYZ in the first place.
I'm pretty sure Buffy and Willow interpreted our not talking to them as us being stuck-up sorority snobs or something. In any case, they didn't come back to us for round 2, and wound up dropping out of FR. Later, we invited them to a COB rush event, and they turned us down.
So we lost them because we followed the rules.
Needless to say, by the following year we had a rule that no one was to go near a situation like that until after bid day!