Hello, and I hope I can help you today.
First of all, it is extremely difficult for anyone who did not have medical training to recognize the
hymen or tell if it is intact or not. The hymen is a ring of tissue around the opening of the vagina, and the size of the vaginal opening varies between women. A pelvic examination by a trained physician would be able to tell you if your hymen is intact, however they would have to put a finger inside your vagina to feel your hymen rather than see it visually. You may be able to feel it yourself by inserting one or two of your fingers in your vagina and you should feel a tight band around your fingers that feels like a plastic ring if you have an intact hymen.
Even women with intact hymens do not necessarily rupture it the first time they have sex. If their vagina is relaxed and well lubricated, sex may not necessarily be painful either. So for that reason, it would be impossible for your partner to tell whether or not you've ever had intercourse before during sex. So, you may not have bleeding or pain when you have sex with your fiancé for the first time even if your hymen is intact.
So if you need specifically to know if your hymen is ruptured, the only way that can be accurately determined is by an examination by a physician or women's healthcare provider. But I hope it eases your mind that no matter what happens you can advise your fiancé, even if you do not bleed when you have sex, that you can still be a virgin.
I hope I was able to adequately answer your question today, and that this information was helpful.
Best wishes,
Dr. Brown