they have their reasons.

he knows if he goes back to her now, she might not take him back, it might not be the same.

his boss tells a joke about what his parents got him for his fortieth birthday, something about a gym membership or a hair implant. like all his boss' jokes, he knows it wont be long until he hears the joke told again, word for word, to some captive listener on the phone. It's as though the jokes stay in rotation for a couple days, then retire.

she fell in love because it was the easy thing to do. she doesn't know any more about happiness than him, but she doesn't think about it near as much.

if he would have gone to paris his life would be different, he wouldn't have married her, he wouldn't have divorced her, he wouldn't hate his job, he wouldn't mock everyone when their back is turned, he might not be bitter. he also wouldn't have his daughters, they're the reason he puts up with it. to him it's a good reason.

she's learning to go out in the world and not have to worry about loving or being loved. she's learning life can be ok like that.

he's trying to sell himself the idea of things getting better, but he's not buying it. he's giving it away.