Why is it ridiculous?
I gotta tell you, here in Brazil that story doesn't sound so ridiculous. Ronaldo and Milene's marriage is known to be an arrangement. Milene got pregnant as soon as she could after they first met, so she could cash in on the millionaire player. They were together for like two WEEKS before she got pregnant! Add to this the fact that Ronaldo was under a lot of pressure by his agents and sponsors to 'settle down' and marry.
The lovely Susana Werner didn't want the 'housewife' job Ronaldo offered, he was jealous of her modeling career. And Milene's superfast pregnancy put him in a no-choice position; she announced it as soon as it happened so R9 couldn't get out. So they married, because he needed to 'upgrade' his image to 'married man' - the downside of being a superstar, I guess - and Milene wanted the millionaire marriage.

Ronaldo cheats on her every chance he gets. And now she apparently cheated on
him.
I may be wrong, but it doesn't sound so unlikely. It was a fake marriage, generated out of convenience. He was unfaithful and it stands to reason that she would be too. And it also sounds believable that R9 wouldn't deal well with being cheated.
Why do you guys act as if this is impossible? Is Seedorf gay or strongly religious?
