Need help on P3R for cheating.

Soo things have been fast between me and Chihiro, all of a sudden she told me that she had a crush on me. I didn't really wanna reject and now we're dating. I'm pretty sure that everyone in the P3 community is simping for Mitsuru, so do I. Long story short what happens if I try to get closer with Mitsuru? Is there anything I could do so I don't get caught?