No, you're aren't understand. He will feel inadequate no matter what woman he is with. The fact is that simple, there are probably no women at his age, almost 30, who have never had sex. And odds are, if they have had sex, one of the guys they were with is better than him, or has a bigger dick than him. So every single time a conversation like this comes up in a relationship, what does he do? Jump ship every time? His partner has absolutely no issue with him in the bed, that is the problem. She doesn't say he is inadequate, she likes him and is happy with him. At no point did she say she is unhappy with him in any way, she just said the other guy had a bigger dick than him and was a better lay, and she literally didn't say it to his face and when confronted lied to his face in order to protect his feelings. That is it. Sure, it's nice to assume your long term partner is your #1 in bed and nobody has been better, but I honestly think it's completely delusional to assume. With that logic, it should be assumed with every relationship, meaning that no matter what, whoever a woman ends up with last is the best sex she ever had? That is so bizarre. It is just sex. If he thinks she doesn't love him because another guy had a bigger dick than him then he has the issue and needs to see a therapist. How can you love somebody unconditionally and have something so insignificant destroy your relationship? I think OP is 100% at fault. He is right to feel sad, but to this extent is too much.