I will say, as a woman, I can’t masturbate while standing or sitting. I have to lay down. That’s probably why your wife masturbates in bed even though you masturbate in the bathroom. That being said, she shouldn’t be lying about it or doing it while you’re right there (unless your comfortable with that). I wouldn’t even keep asking her/questioning her. Just tell her “if you want to masturbate please do it when I’m not in here.”