In the official novelization of Raiders of the Lost Ark, Marion is 15 years old when Indy starts sleeping with her, and he abandons her a year or two later. In the film, Marion claims that she was a girl during the affair, and Indiana doesn't deny it. Marion Ravenwood is a fictional character who first appeared in the 1981 film Raiders of the Lost Ark. Played by Karen Allen, she enters the story when Indiana Jones visits her in Nepal, needing her help to locate the Ark of the Covenant with a possession originally obtained by her father, Dr.
After 27 years of absence (21 years in the internal chronology of the films), the character returned in Indiana Jones and the Kingdom of Crystal Skull and was once again played by Allen. So we have three of the creative minds behind Indiana Jones, and the conversation revolves around the fact that he is a statutory rapist. The conversation is how young is too young and how old is too old. But whatever the age in that range, it's very clear that what Indiana Jones did was wrong, even if it was promiscuous.
This isn't even the only time his attraction to younger women has been addressed in the novel, although one could argue if it's canonical. Also in the novelization, Marcus Brody finds Indy in his bathrobe at home because he just entertained a co-ed. Possibly the girl who writes 'I Love You' on her eyelids in the film. However, there is another character in Raiders of the Lost Ark who actually does much more to make the Nazis uncomfortable.
Although Indiana Jones is undoubtedly presented as the heroine of the film, it is actually Marion Ravenwood (Karen Allen) who proves to be the biggest thorn in the side of the Nazis. This is partly because she openly opposes it and works against him throughout the film, where Jones simply tries to recover the Ark from under them - a plan that ultimately fails, leading to the theory that Indy did nothing.