@Chain_Shadow pretty self explanatory honestly.. From his standpoint, his sister never apologized to him, only to his wife, and he's unaware of that. And after telling him he'll never know what its like to have a kid, his sister announces her pregnancy, which was a slap in the face, only made worse by his mom. From his standpoint his family is selfish, and completely ignores how he feels. In short he's angry and jealous, and feels like his sister did this to spiteful.
So, he stopped caring.
Thing is, his wife and daughter has been manipulating the entire situation since they arrived there. Touka drove a wedge between him and his sister by making those crazy statements in front of her, and by showing her watching her parents in the act.
And the wife swooped in and mediated the problem and manipulated who gets told what.
Him coming to terms that he just doesn’t care about his family anymore, is what Touka wanted... to let go. Because what she wants is a baby. And her mom is helping her achieve it.
Its far easier to make someone do what you want, when you break em down mentally first.