I’ve had two permanent relationships in my life. In each of those relationships my partner and I occasionally walked in on the other masturbating. Our responses usually when something like, “Want any help with that?” or “Oops, sorry to disturb you, unless you wanted company of course.”
I know some people have hang ups about masturbation, but it’s difficult for me to understand how or why somebody’s romantic / sexual partner would object. It’s not as if they aren’t already accustomed to seeing their partner in sexual situations.
I guess if sexual intimacy had been scarce lately, and the masturbating partner had been turning down opportunities for intimacy, that might be a sign there’s a problem.
But if the relationship were otherwise actually healthy? Bring on Rosie and her five friends!