I feel like that ahole playboy might show up and be like "Oh, Tamaki is a different girl? You won't mind if I pursue her?" Forcing issue to be resolved.
I wouldn't be surprised, if that is what MC is thinking. In order to fix the situation, is to make the other personality also fall in love with him. That way, when the switch happens, it wouldn't be too troubling. Or it could just happen naturally, and the NTR bait will be between the personalities, which would be interesting.