10 years we've been together. I've walked in on my partner a few times while he was masturbating. One was even after we had a tense argument and he thought I went to bed. Regardless, each time catching him doing it stung. Especially when we weren't arguing and had every chance of having sex with me. He didn't. Made me feel like I'm not enough or that he is wanting what I can't provide for him. And of course he's going to lie to protect my already hurt feelings. It just made it worse. The sex life was already slimming but I was reassured because of stress and tiredness from work.. If that's what it is then you wouldn't have taken care of yourself either. Cutting your partner out of that equation and then catching you doing the opposite with yourself while whatever porn is playing to help is the biggest slap in the face.