I would never suspect somebody of lying about their virginity, and I respect the choice to remain a virgin. I especially respect anyone who can ignore the social pressure to "lose it just to lose it" after a certain age.
I have to be honest though and say that I would be hesitant to be somebodies "first." Sex means different things to different people, and I think that until you've had sex that would be really hard to identify for yourself. If I were dating somebody who told me they were a virgin, I would not necessarily stop dating them, but I would make it a point to move slowly and communicate a lot about our actions.
If a 29'ish person told me they were a virgin I wouldn't have any reason to disbelieve them. It's a personal choice and there are various reasons someone might choose to remain a virgin.
Why would anyone want to lie about being a virgin? Usually people hide the fact that they're a virgin. Unless they've made it a choice that they're not gonna shag until they get married then usually it's more connected with shame and pity than a pat on the shoulder and "good on you for keeping your legs closed!" One thing is if the person is very young, but I wouldn't doubt it if a person in their 20's admitted that they were a virgin.
No it's not hard to believe that someone is a virgin...
I have an auntie in her 60s who's still a virgin and she says she's unlikely to ever be with a man now...
I felt sorry for her when she told me that, but she said that it was her choice and she's happy with it...
Maybe: It's a Scottish thing (although I think not). I have an elderly female relative and a neighbour who are almost certainly virgins: never married or even had a proper boyfriend. In previous generations, it was almost expected for career women (especially teachers and nurses) to remain unmarried. Sad in some repects, but their choice...
The liberating amazing thing about our sexual personalities is that belong to us and we make the decisions. I respect some choose to wait. I was a teenager but we all make our own decisions. There is no right or wrong choice. Only the choice that works in your situation.
.... and if you prolong your virginity beyond 25, all the characteristics of a determined or introvert person can be attributed to you 