I think this is natural for women, sometimes my wife like a crazy wants me to cum inside. So she just holds me very hard if I am about to pull out by mistake.
And yes, according to her this is great warm sensation and satisfaction, she feels pulsations of the cock and sperm, she usually watches me at this time too. I enjoy it as well.
She is the only women I cum inside and had sex with. She was taking contraceptive pills apparently at the time we started to date. So first sex was in condom but second one she said it is ok without as she takes pills. And I think just 2 weeks later she asked me to cum inside. For me this was a thrilling thing. As it turned out much later 3 of 4 ex boyfriends of my wife did the same and this is exactly why she was using pills.