From IMDB:

Ben Affleck has applauded film bosses for ignoring his fiance Jennifer Lopez’s part in new movie Jersey Girl - because she only appears for 15 minutes. Skeptics felt sure marketing experts at Miramax were trying to distance themselves from Gigli, Ben and Jen’s disastrous first movie collaboration, by leaving her off movie posters and ads for Jersey Girl. But Affleck insists the idea not to capitalize on his girlfriend’s bit part was a smart one. He says, “To sell Jennifer on Jersey Girl would have been disingenuous. She’s in the first 15 minutes of the movie, a cameo. It’s actually more honest, and I think it makes everybody more comfortable at this point to make it about what it is - a father and his daughter.”