Romance movie about a man learning to romance from his fathers journal


Hello everyone, I need your help to find the title of a movie i saw many years ago. It was about a man that is pretty assholish and his wife decides to divorce him, he truly does love her so he seeks advice in how to get her back, his father then tells him that if he goes through all the steps in a journal he wrote when he was younger he can achieve it, so he tries it. In the journal its describes specific and different tasks that one must complete day after day in order to get a woman's heart, one day he has to get her flowers "just because", other he has to ask her about her day, etc. at first he does just the minimum effort possible and his wife is really confused, her friends tell her that he is probably trying to "ease her up" and faking niceness so that she doesnt ask for too much in the divorce terms, she gets angry and doesnt believe him anymore, and then she finds a doctor and starts dating him, our protagonist now is really angry because the guide in the journal is not working, but his dad tells him that its because he is just doing the minimum effort possible instead of actually doing what the journal says, he tries again and it starts to work a little, in the end they get back together after the last step in the journal.
To be honest i dont really remember if it was a journal or a book his father wrote, it might even be a "guide to romance" that he wrote or something like that. But the rest of the details i think are correct.
Thanks in advance for your help.

The movie itself doesn't ring any bells, but the premise reminds me of the song "One Hundred Ways" by Quincy Jones/James Ingram. I wonder if there's any bizarre chance searching the song could lead you to the movie? (Probably not -- I am a bit drunj at the moment.)
"You seem a decent fellow. I hate to kill you."
"You seem a decent fellow. I hate to die."