If I am sharing my living space with other adults and my door is shut I expect someone to knock first. If I have my own bedroom, I don't think I need to wait for dark or until someone decides to leave to be sexual behind my own closed door. This idea that one must wait for others to be asleep or gone is foreign to me as a married person.Dressing and caring for hygiene don't usually take that long. Parents (or even married couples sharing the dwelling) usually plan to be intimate only when they are fairly sure they wouldn't be walked in on, would use a lock on the door, or wait till other people are away or asleep. I would think the same principles might apply to a single adult who wants to masturbate.
Anyone who cannot accept that a closed door means privacy is expected has issues with being invasive.
it isn't just about sex. I have to have time alone or I feel drained. I can be in the same room with my husband for long periods of time in shared quiet time but I can't do this with other people. If I had to live with someone else and they couldn't let me have time alone in my room, and yes that's hours of alone time, I'd go insane.
Her way of showing her concern is controlling and invasive. if she has issues with how he is spending his time and running his life, she ought to be upfront and speak up instead of using passive aggressive ways to insert herself into his private time.My best guess is that the issue here has more to do with his mum being concerned about why he seems depressed/irritable and seems to need (in her eyes) an inordinately large amount of time alone. His defensiveness may make her concerned that he is either doing something wrong or harmful to himself. I agree this is not a great way to express her fears, but I think they are more likely fears than maliciousness.
it's a bad economy. He's completing his degree. It isn't like he's totally shutting down in his life.