In my opinion, tampon use will not affect your virginity. This myth has been around longer than either one of us. Your hymen is a thin membrane of tissue that covers the inside opening of your vagina. This myth is from the belief that, once the hymen is broken, a girl is no longer a virgin. I do not believe this is true. The hymen can be broken by everyday activities such as riding a bike, and yes, tampon use. Neither of which have anything to do with sex, intercourse or virginity. When it comes to your monthly cycle, choose an option you are comfortable with, whether pad, liner or tampon. Feel free to use tampons, read the package insert, and look at the pictures. Family, friends and your healthcare provider are great resources.
After my first period, this question popped into my head too! My mom had a box of tampons for me so I pulled one out and thought, "It's going to break me, there is no way that stick-looking thing is going in me without poking something out!" Reluctantly, I called my mom to the bathroom to ask her and she reassured me, this will not change you. "Take your time, relax and just try." I did take her advice and it did take a long time, and she was right, nothing fell out or hurt me! To me, my virginity was something that could only be taken when I had intercourse, and the tampon looked like a daunting opponent that truly might break "it". I know that I cannot give you the medical breakdown so I am going to encourage you to check out Health Expert Michelle's response too. Last thing, if this really bothers you; remember pads are still a good option. There are so many comfortable options versus the huge pillow ones I had to use years ago.
Personally, I define losing your virginity as the point when you choose to (and do) have sex for the first time. So, based on my definition of virginity, using a tampon will not affect it. There's this misconception about tampons being more invasive than they really are. In my opinion, tampon use will not affect your virginity, because the only thing and person in control of that is you.