If you play the Alyssa event, it turns it's not actually a lesbian event, much like the Yoga event isn't if you play Dylan's POV. The Alyssa event is more about getting Filthy points for the straight route (and meeting Alyssa's boyfriend), while the Ellie/Julie event is more about the Lesbian Temptation route.
What I'm finding curious, is that the more I look into it, the more it looks like Marie might change her sexuality depending on which path you're on. On the Filthy/straight path, you can set her up with Dylan, whereas on the LT path, she certainly doesn't seem to mind Sophia staring at her and some accidental touching.
What is this "still have Nathalie and Vicky"? Are you playing the GW route?