@neptuneblue,
Quote:Not your circus, not your monkey...
I see a bit of your point in this and how you state you are making a lot of assumptions. I think that is why most of us are trying ways of suggesting how she can speak to him. I don't think the goal here is to break them up, but to let the cousin know he is potential hiding this pretty bit thing in his life.
I honestly do not like the above quote - it is sort of like a way out rather than making any sort of help. There are situations where this is true - but I think this situation is very close to a fine line.
For example, if someone is on the street getting kicked and beaten by someone else - do you say oh not my circus not my monkey and walk away and do nothing? Probably not - this is a life threatening situation and we should feel a personal responsibility to help - whether it is calling the police or jumping in - if you strong enough to put a stop to it.
This is not life threatening but is life impacting. I think encouraging this man to share the truth (if he has) is the best route. Explaining hiding something is not the best way to start a marriage and it is better to work things out prior to getting married.
I am not huge on reaching out to the cousin just for the reasons you state - if you are wrong in any assumptions (who knows maybe this guys is just grandstanding on this website) -or maybe he has discussed this with your cousin and she is ok with it.
Can you find him on facebook or maybe through any alumni addresses/phone numbers if you university has such a contact list? Try not to be confrontational on it - and try to be respectful of him - but concern for the both of them - for example if he does have this hidden life - it may be best for him to pursue that rather than getting married.
Sorry you had to see all this - and I wish you the best on it.