What are the details of Indiana Jones' relationship with Marion?

In Raiders of the Lost Ark, there are a few clues about Indy's and Marion's relationship before the film. Wikipedia says that Indy fell out with his mentor Abner, Marion's father, because of his relationship with Marion, who apparently was too young for him. Does anyone know, is this correct and are there any other details? How old was Marion, and what was it Indy did that was "wrong and [he] knew it"? Wikipedia says this is referring to her being too young, but I'm not sure if they're interpreting that wrongly. Geeky question I know but I've been wondering for ages!! Cheers for any answers.

I thought you caught the gist of it. She was too young, Indy and Abner Ravenwood had a falling out largely due to her. This is just specualtion but I think Marion was late in high school or just starting college (mid-late teens) when her and Indy dated, probably when he was in graduate school studying under Abner (mid 20s). I
The whole story is never revealed in the films, but I am sure we will find out much much more about their relationship in the new movie due out next year, Indiana Jones and the Kingdom of the Crystal Skull (May 2008).
Marion (Karen Allen) is in the film and William Hurt is supposedly playing the role of Abner. The new film takes place in the 1950s, and seeing how Abner was believed to be dead in the time frame of the first film it might be flashback or something showing the three characters' early relationship.

u know what that is a very good question. i want to know that too

Indy obviously had an affair with Marion when she was a teenager, but according to him, she was old enough to know what she was doing. She probably idolized him, fell in love, and he took advantage because he worked with her father who thought a great deal of Indy.