Hi there ~
I understand your concerns. I believe that you have posted in the wrong section since this is the section of "Men's Health". However, I do believe that it is related to your fiancee's condition. I also believe that having intercourse may be the reason that you are having the problem with bleeding, and not the extended period. This does not necessarily have anything to do with the size of your fiancee's penis. I believe you need to consult a doctor, a qualified psychiatrist
or an OBGYN
who can help with the condition. I hope this helps.
Take care and have a lovely day!