I have these two scientists who are romantically involved. They are both kind of old. I notice that frequently the female doesn't get in the hut before the male exits. Errr, I don't want to be indiscreet here, but what is going on? Is she actually being "bred?" She does improve at breeding.

Don't worry - her speed doesn't affect her 'performance' at all! Just because she's slow doesn't mean she doesn't still have what it takes! It looks odd, granted, but the trip is still worth it!