Girls who wants nudes and masturbation

I have had a few cases of girl who show sexual intent over Tinder , and get me on snapchat and send like heavy fingering pussy action videoes. I tend to respond with nudes, dickpics and jerking off. And we go back and forth with this until we/I come. Then afterward when I try to get her over another night she goes all silent. Is it a better approach NOT to send nudes, even when they want it? I`ve gone done this road a few times, and they always end up flaking.