It does not get better than this

The New York writer Melvin (Jack Nicholson) suffers from obsessive-compulsive disorder. In restaurants, he always uses his own plastic cutlery, he washes his hands with a new bar of soap every time, and he avoids grout lines at all costs. His neighbors hate him. He does everything to make himself unpopular, even going so far as to dispose of his neighbor's dog in the building's trash. The only person who can stand up to him is the waitress Carol (Helen Hunt). She is a single mother of an asthmatic boy.