Sex is a great stress reliever and afterwards can help you get to sleep.
It's not always necessary to personally feel like having sex, if you know it would please the other person, and it's not putting you out. You might think back on a time he has done that for you.
As far as the porn, it disgusts you, but obviously not him. That's an issue you have to work with, and not impose your personal values on someone else.
Would you prefer for him to:
(a) look at naughty pictures and masturbate
(b) look for another sex partner
(c) just live with the fact he is sexually unfulfilled
Those are your choices. Pick one.