Film from the 2000s. One boy was fat and unlucky, the other more self-confident. Both were in love with a girl. I remember several scenes. When they ate at the train station, the fat boy got a sandwich in a huge roll of foil. When a woman took them in, the boys were swimming in the pool, the woman came in and they sat down under the water, and the woman said, they say, what I didn’t see there. Then the three of them went to sleep on the same bed, and the girl lay down between the boys so that one of them would not be offended.
Maybe “Terri”?
https://en.wikipedia.org/wiki/Terri_(film)