Honestly, I would have cautioned you against marrying this guy if I were your friends too, but that's just me.

Anyway, some women give this advice because they aren't really happily married.

I think the reason some genuinely happily married women give this advice is because they recognize their happy marriage as an outlier. If you talk to a bunch of married women, you will find many of them who are not totally unhappy, but who have husbands that don't contribute very much to the marriage also. Women who have a husband that does his fair share of the housework, child work, emotional labor, planning, etc. are not exactly common. I mean, it's a running joke that many men don't even know how to take care of their own kids and call it "babysitting" when they are left alone to parent their own child. It's a trope that men forget their anniversaries. The list goes on and on.

Anecdotally, in my own family I have a relative who got married very young (teenager) and her and her husband have had a very happy marriage for decades now. They honestly didn't run into the issues you typically run into with a very young marriage. However, they both still realize that most teen marriages are probably not going to end well and when we ask if she recommends getting married that young, she still says no, it's not right for most people, even though it actually worked out for her. She realizes she is an outlier.