I would not feel comfortable camming in front of my partner because
1) I would want to look at him
2) I would be more likely to show/do things in public chat that I wouldn't normally do.
3) I couldn't handle seeing him masturbate without logging off and promptly getting fucked.
4) If he didn't masturbate, I would wonder if he was being turned on and if not, why not?
5) Why are you sitting there watching me for hours? Go do the dishes, laundry, something productive so that I don't have as much to do when I logoff.
That being said, my boyfriend does occasionally watch from his computer if he's home from work. I find that very hot, especially when he tells me that he may have masturbated.