Nah, she apparently literally turns into a human and can turn back into a pillow at will.
...Which makes me think that at this point, it would've been better for him to just let mother see her in her human form. At least she wouldn't have to be disappointed by her son's weird fetish play with pillows.
@Abedeus letting the mother see his son stripping a high schooler(jk)? The mother may end up calling the cops and question herself for raising a son that prey on jk, even if she doesn't call. she probably ask the son to take responsibility and wanting to do the meet the in-laws nonsense etc.
The "Dressing the pillow and being a closet perv due to pend up stress" act seems easier