The vast majority of people consider romantic and physical relationships to be a high priority in their 20s, some even get married that early. If you're a virgin past the age of 30, by definition you are different and thus people will inevitably think something is most likely wrong with you. Being preoccupied with your own virginity and feeling like you have to justify it is one such wrong. If you don't fuck, might as well own it. The moment you reveal you can't fuck, ironically, you're fucked.