What do you suppose would happen if whenever a sex scene came up you didn't let it get to the point where his mental block kicks in? Before it gets there you start kissing him and sliding your hands underneath his shirt while saying something like "this is making me so wet...so hot with desire for you...I don't think I can control myself" as you pull his attention away from the TV and go from there. Keep the volume relatively low so that an abrupt "OH GOD FUKK ME!!! HARDER!!! HARDER!!! HARDER!!!" in the background doesn't trigger his mental block. Think it could work? If so, maybe actually having sex with you this way could help him clear this hurdle of his?