What caused this?

Everytime I had sex for the last month before I broke up with my boyfriend, I would get thrush a few days later. It was so uncomfortable. We used condoms everytime we had sex though.

Then he broke up with me, but why sudden thrush despite having no symptoms the whole relationship?

I’m a bit sad too because he’s the only man I’ve dated who I didn’t get urine infections after everytime I had sex. I never had a UTI with him , I thought that meant we were meant to be :(