It's money. Think about it. What are they honestly going to do if they got divorced? Kayla takes everything and divorce rapes Nick. Nick gets fucked over. Kayla can do nothing with the rest of her life still. She still has five kids, and hasn't worked in nearly two decades. Even with child support, five kids is a lot. It's also not like she's going to find a new man any time soon. Men will tolerate a single mother of 1, mmmaaaayyybbeee 2. But five? Fuck no. She also can't handle daily life now, forget being by herself. Neither have any incentive to get divorced. Nick would be financially ruined and Kayla's physically useless.
I can see them both saying "Well....we don't love each other anymore. But divorce is too messy....so what do we do?" Hence, the Qover.