I sense Breast Envy from the mom's rival. Are those padded? Check her.
Also, at least MC's mom is actually around and cares about ber, which is more than can be said of most anime parents, who usually move halfway across the planet and leave their kid by themselves for their entire highschool life because of their job or whatever excuse to not actually do any parenting. Being jelly cause the dense useless dude you want the dick of is more interested in your mom is some 1st world problems.