It seems to me that we can speculate forever about
what MIGHT be going on here, but it's really impossible to tell.
If two people are being intimate without knowing the answer to basic questions such as these, they might want to take a step back and get the answers before proceeding with the relationship. That's just my take as a father and a grandfather. I'm not trying to be moralistic, just realistic. In the 21st century, it's important, absolutely essential, to know this stuff before becoming intimate. If the partner is, for whatever reason, not forthcoming, that to me would be a major warning sign.