I doubt Vshojo had a explicit "You must Dump your BF" Clause, maybe it was more about the fact they all now had a S/O to help keep them stable so leaving Vshojo wouldn't impact them as much, i still believe in my Rev Split theory but that is a interesting detail that shouldn't be ignored.
As for if Any Holo members are dating, I doubt it, Closest you maybe get on the English side is Mori and Kiara back when Kiara lived in Japan, but even then I am not willing to bet on that. I feel like none of them are really all that likely to be romantically involved.