Actually, Monica only realized what the stain on the dress was several months after and it was her friend Linda Tripp who encouraged her to keep the dress: https://metro.co.uk/2018/11/13/monica-lewinsky-shares-x-rate...
I got the direct impression from the news that Monica Lewinsky was this pretty young thing, very innocent, who had a tryst with the POTUS and was freaking out. Linda Tripp came along and under a false veneer of sophistication and helpfulness, instructed Monica on what to do, move-by-move.
The story was of an ingenue who was, in turn, under the thrall of the POTUS and then Linda Tripp.