My best friend was non-suicidally depressed for 2 years, and I just did not believe him. I thought he was just having trouble getting over an ex for some reason

My best friend was non-suicidally depressed for 2 years, and I just did not believe him. I thought he was just having trouble getting over an ex for some reason, because him being depressed didn't make sense. The thing that finally convinced me, and ONLY in retrospect, was hearing the full story about him and our best girlfriend during that time. This girl is, pardon my objectification, an 11/10 in every way. Everyone we know is in love with her, and with good reason. It turns out, for a large portion of the time my friend was depressed, she tried really, really hard to date and/or have sex with him, and he repeatedly turned her down every time. He'd been attracted to, and probably in love with, her since I can remember and still is, making hearing that this went on for YEARS shocking to me. But both sides confirm: it happened. It turns out, her wanting him made him feel like she was playing a joke. "How could she possibly want to have sex with me, or like me in any way? Here's the answer: she doesn't. She's playing a joke on me, and I don't fucking care for it" he says was his inner-monologue at the time. We still look back and just marvel about that time, because it was so bizarrely different the reality we've lived in all the other days of our lives.