Curiosity killed the cat?

Abi

I’ve been with my partner for 4 years. I finally moved in over a year ago. He had mentioned his last sex act was a blowjob a few years ago prior to me. When I asked who “she” was he said why? Why did it matter? It is in the past etc. But I can’t seem to understand why he can’t just tell me who this girl was? And I know theirs women out there who freely do this but I’m curious how this girl got in his car & did this w/o him having an interest in her? Would any of you still be curious?