Older movie. Man gets a divorce. Pals work to find him the "perfect" wife. He remarries, they have a child then He starts worrying that she is fooling around. Turns out she is and with his best friend. He's been set up and the friend and wife put him in asylum and plan to take all his money. In the end he kills the wife in the yard of the asylum.

Sounds like Dream Lover (http://en.wikipedia.org/wiki/Dream_Lover_%281994_film%29)