Movie about three-person relationship?

Many years ago I saw this movie about a girl not being able to decide between two guys she just met. She decided to tell the guys about each other, also proposing a three-person relationship. I remember she said that the guy refusing it is the guy who really loves her and she will keep him. But both guys were okay with the relationship and so they were all together. Eventually she got pregnant and didn't know who the father was and they also decided they did not want to find out. Spiritually they were both the father.

This is all I remember. I can't remember any actors, names, how they looked like...nothing. But I would like to see that movie again and google didn't help me find anything :-(

Please help :-)