She had a suspicion that they may have been tampered with, such as poking holes in them.  I never allow partners to use their own protection, even in my personal life.

I'm putting my money on a guess that she is sensitive to using a variety of different condoms. No two condoms are alike, even different styles by the same brand. I found in my experience that using different condoms caused me alot of irritation that led to yeast infections. When I stopped using different brands, and stuck with one and only one type, the irritation cleared right up and I had no more problems. So on the rare ocassion when a gentleman asks me to use to his preferred brand of condom, I respectfully decline and insist on using my own.