My wife is currently attending university (final year) and, over the course of our 8 year relationship, she has inadvertently drawn the attention of a number of individuals who seek a relationship with her (she's quite beautiful by all accounts). These have mostly been school or college boys who can be brushed off, but over the last year and a half one of her university peers has become quite forward in his advances, including kissing her while under the influence, driving her home via a scenic detour (including stopping for a chat) and attempting a physical advance on her after dropping her off at home on another occasion. She took to voicing these latter two situations on social media, particularly to their peers, which was enough to make him back off.
Now, these events and his continued advances at university have been enough to make her keep her distance, though he still stays as close as possible, even sitting next to her in lectures and trying to engage her when she ignores him.
The big picture problem is that she is good friends with his fiancee, and they also have 3 children (2 are paternally his), one of whom gets along with our 2.5 year old quite well. Because of this we feel telling her about his advances would be detrimental to their relationship and cause problems for the children - we really don't want the children to be hurt. We also feel if the friendship persists he will view this as my wife being comfortable around him and his advances - she certainly is not.
So, how does my wife maintain the friendship with his fiancee, and the friendship of the children, without him becoming too comfortable or feeling empowered around her.
If it helps we are in Yorkshire, UK. Me and my wife are 23 and 22, respectively and the admirer and his fiancee are 26 and 30, respectively.
So thank you all so much for your input, I can hardly believe the popularity of this question. So after some deliberation we're going to go ahead with the accepted answer if we see ANY clues to the behaviour continuing. The last concern was the drive home and was months ago.
Many answers and comments took quite the diversion from my actual question, which was simply "How does my wife remain friends with her admirers fiancee?" - the admirer may not have made an advance in months but the negative feelings my wife holds are preventing her from wanting to socialise with the fiancee. I don't need to be told to stick up for my wife nor be advised that she is a "slut" from those who don't know her. I didn't need advice on handling the admirer - I can handle him - it was about his fiancee and I feel that the selected answer provides the best solution.