I learned that he had feelings for her that apparently many people were discovering, but she didn't know. I expressed that this put me in a difficult position with Kitty and asked him what he thought I should do since I was reluctant to lie to her, saying that I thought he should tell her himself. He interpreted that as an ultimatum, then declined to tell her, and lied to me saying that he had.

I have no idea why he thought I wouldn't immediately corroborate with Kitty just for the purposes of sorting out our own relationship boundaries in the wake of whatever decision they'd made.