@Bella*chick is spot-on.
Brady came back for himself. He has every right to, and I certainly can understand his desire to further his legacy. He's already achieved the most absurd, unbelievable, spectacular of feats, but I can sympathize with his obsessive compulsive desire to squeeze every single last drop out of his career, trying to set the records - and his legacy - as high as possible. Not only that, but with each passing season he adds to the,
"I played until 'x' age" tally.
That leads us two places:
If Brady did in fact guarantee his family more time/commitment and then balked, I completely understand Giselle's frustrations and decision to move on. I also feel bad for his kids; while I'm sure they get quality time together, they certainly get less than someone working a typical 9-5, or even a less insanely committed NFL player.
Brady (especially over the past 5-7 years) built a public image of being a family man, someone who deeply cares about his wife and children, and would publicly state the importance of family in his life. I, too, very much believed (when listening to Brady speak) that family meant a lot to him - it felt very sincere and genuine. This decision rightfully casts some doubt on that family-man narrative. I don't mean to suggest he's a bad husband or a bad dad, but he is choosing to prioritize his legacy (in light of what he's already achieved) over his family - ultimately leading to the outcome of divorce. It is sad to watch from afar, and I don't mean to say "Brady is sad" in an insulting manner, but rather that the situation is most certainly sad.
I hope he is at peace with his decision, and I mean that completely sincerely.