She may very well have been like me...
Clit stim ONLY works when I'm the one doing it, anyone else tries it and that orgasm ain't happening any time soon, if at all!
I rarely get off from penetration, it takes work and concentration, one move at the wrong time and we're back to square one again!
Now there are things that work every time, without fail... Maybe she hadn't discovered hers, or maybe you just didn't do it for her.