Need title of Movie

The movie was about a struggling writer who hadn’t yet wrote anything and was just living day to day in this dead end job. When he meets a beautiful latin woman in his day to day passing smoking a cigarette. She notices him and they develop this day to day banter that leads to a relationship. The woman is married but is in an open relationship herself. They can do anything as long as it is confined to this hotel room or apartment and at certain times. For months, they spend time together in this apartment/hotel room sharing everything. She learns that he is a writer who has not yet written anything. They fall in love with each other. The movie shows them often going to the Guggenheim Museum. The lovely latin women who is falling for this character, who looks like he was in the movie spider man, eventually brings him to meet her husband and their family. It turns out the husband has an assistant that he is involved with as well, and they end up being introduced to each other. After the latin woman and this writer end their relationship, I believe he fell so hard that he asked her to marry him. She turned him down but kept the ring that he gave her. I recall the last few scenes of the movie where he is with the husbands mistress and they have a child together. He finally wrote the book that ended up being a big hit. And he ends up bumping into her and her family at the Guggenheim Museum where she is wearing gloves but still has the ring. It appears that she has never forgotten him or stopped loving him. After their moment he talks about his book and that every great book was probably written for just one person. Apparently, in the movie his book was written for her.