Is her mouth tilted to the side or does his dick have a 120° bend in it? From those positions, his dick should be going past her mouth, not into it. I've seen this sort of thing before, where both characters are facing the camera somewhat yet somehow one is able to suck the other off as if they're facing each other, but not to this degree.

It also looks like his dick is drawn off-centre.

On the plus side, the shading is okay.