Book I read a while back

[oreancle]

I don't remember much about this book, but it was about a guy who keeps on going on long trips, and his wife thinks he's on business trips. He left to go on one of this trips but didn't come back. His wife goes to look for him, but she finds someone who looks like him but not him. He is her husband, but he doesn't know her because he has DID which dissociative identity disorder. The guy she married is one of the identities of his disorder, but the original one doesn't know her. So when his original personality appears he goes back home to his girlfriend, mom, and dad. They know he has this disorder but he doesn't and they are not that accepting of it if I remember this correctly.
The book is fiction, and the main character later finds out that he has the disorder because of his dad. Hopefully, you guys recognize this.