How old are both of you. People like to say that age doesn’t matter, but it does, especially if one person is more mature/ready/experienced than the other.
Is your boyfriend under 18? If so, and you are 18 or older, there can be legal consequences for having sex with a minor, even if you are the female.
There’s a few things that could be going on. My first guess is that because he is a virgin and he knows that you are not, he could be quite intimidated by that fact. Even if he says he’s not. To admit that he’s intimidated might make him feel, in his own mind, like he’s kind of a loser. If that is the case, you need to gently reassure him that it’s not a problem at all.
My second thought is that because don’t have any particular interest in having sex with him one way or another then he might think that sex isn’t all that great. I’m curious as to why you don’t have any particular interest in sex. Most people, once they’ve gotten a taste of it, and it was good, want to get more of it until the day they die. He may also think that because you’re not particularly into it one way or another, that he is not desirable to you and he doesn’t want to push the subject because if he found out for sure that you aren’t sexually attracted to him, then he would be humiliated.
The next thing is that he may not be ready for sex, especially if he is really young like 15, 16 or 17. The media portrays that young guys are always interested/ready for sex starting around 12 or 13. I don’t think that is the case for all guys. But even if he isn’t ready for sex, physically or emotionally, it would be very embarrassing for him to admit that to you.
Now, here’s what I really think. He might be gay, and not quite comfortable with it or even able to label it yet. He might still be figuring out his sexuallity. He probably really loves you, but does’t feel the typical male/female sexual attraction to you that he might with the right guy. Most of my gay male friends dated girls and even had sex with them and at least one even got married and had children. Back in the 70’s when my friends and I were growing up, it would have been traumatically embarrassing to have anyone find out that you were gay, or to label you as gay even if you weren’t. Things have changed, but not much when you think about how one of our political parties still sees gay people as sinful and not quite fully human. Being young and gay in the US still sucks. Most people aren’t brave enough to jump out of the closet, it may take years. But in the meantime, having a girlfriend can be a very comforting thing. If he is gay, he probably enjoys the intimate friendship he has with you, without having a sexual attraction to you. Plus having a “beard” will keep the wagging fingers out of his face, at least for awhile.
And last, but not least, he may actually have some type of physical problem, such as premature ejaculation that he’s ashamed of. Or he may not be able to get physically aroused by another person because he’s addicted to masturbation, and he may also have some type of hormonal problem that causes him to have a low sex drive. Or, he might even be asexual kind of like Sheldon Cooper on The Big Bang Theory.