I don't even like popping my own pimples, let alone someone else's. I've never even thought about popping a boyfriend's pimples.
However, my last ex told me that his last ex LOVED to pop his. She was about 5 or 6 years older than he was, and claimed it was because she misses her "younger skin"... I dunno, maybe she's part snake and shed her old skin. Who knows.
But thats the only other time I've heard of a girl popping her guy's zits.