Mai

I think because she doesn't want to talk badly about her daughter's father. He is the father of her daughter. It's good for their daughter that their parents never talk bad about each other. In the end its everything for their daughter.

Money talks though. He might be a cheater but he's a generous spender lol. Like he just might have a cheating problem but he's a good father to her daughter

Considering Ae's family is somewhat mafia like I don't think Tu would want any problems by bad mouthing Ae.