A woman can change the size of her man’s penis. But his submission/dominance it tied to the length as well. So if he has a 10” dick that equates to very dominant. But if he’s say a 3 he’s submissive but not a slave to the woman. She generally likes to keep him a 3 to keep him docile, but when he’s that submissive he also wants to see her with a man with a bigger dick. She does sleep with someone else, maybe keeps him a 3 for a month to fulfill his fantasy, but then when she makes him bigger, let’s say 8 or 9, his dominant side doesn’t like she slept with someone else.
So she has to put him back to a 3 and keep him submissive to save their relationship, which also leads him back to wanting to see her with bigger men.