oh yeah, if left to their own devices girls will start making out with each other. It starts inocuous enough, just a make out session every 4 days, but if not pursued by the player they will end up with Wanda spending all her time periods in every girl's room other than Emma and Rogue. After a successful? session with the player, though, a woman will not fool around for 3-4 days. Sadly, there are no special scenes when catching them or a chance to blackmail them.
Wanda, Bets and Jean are the most proactive in this regard, starting these scenes after 5? days of no romantic activity. Kitty and Storm are sort of the most resistant/unpopular for lesbians, but will also put out and start spending time daily with Wanda/Doreen if left alone long enough(150? days). Emma and Rogue(if she hasn't been levelled to touch) never go for those scenes either.
I think the chance for such events is(besides an internal horniness timer?) based off of how much they like each other, but only one side needs to initiate. e.g, Jean and Laura will never make out as they HATE each other, but Jean and Gwen will.
a neat caveat of this new system is that the player has a chance of seeing unique dialogue dependant on how much girls like each other, if they are fucking and if they are fucking with the player which imo is more interesting than the stock response "yeah, we fuck".