Well I think that Life can be very hard. And Greek Life just adds to it. Many members after they graduate just need a little break. Everyone knows how difficult the time after graduation can be. We all have to remember that we are WOMEN first. So if a soror has to take some time off to find a job, apartment, and get settled in a new life, then so be it. She can come back to Sigma once she's more secure, and we'll welcome her with open arms. She deserves that much after working so hard (as us Sigma Women do) for up to 3 years.
As for those members that become "permamnently" inactive, I can't offer a reason for them. I just hope that doesn't happen to me.