Single life? I never had one of those. I married the girl I met at a 13 year old birthday party. We started “dating” if you can call it that 2 weeks later. We have been married 30 years. I wouldn’t change anything. Not everyone one has to have this chick filled “single life”as you state.
Im not even talking about a “chick filled” single life. Didn’t even allude to it. I’m talking about him having some of his own time, not tethered to anyone while he’s 21, 22, 23, when he’s going to have more opportunity to do amazing things than 99.9% of the world. He’s 20, so he has no perception of the world he’s about to step into, and also has no idea of how she will impede that world (not intentionally, but simply because she is his fiancé). He has his whole life to be married to her - but not to be a young, single, millionaire who can selfishly think about himself while he’s still of the age where it’s actually better for you not to be married/engaged. Even if he’s just dating her it’s better.
Your story is wonderful - I hope that I reach 30 years someday. But for a majority of people it would be a disaster as the change that most people go through from their early to late 20’s is drastic and early 20’s marriages (20-25 Years of age) end in divorce 60% of the time.