while I was only 21, he was 29. This might be offensive, but while I believe there are many fantastic young mothers out there, I myself would put much less trust in a 19 year old boy being a competent and stable partner and father.
Really good and balanced post, SilverDoe. I have seen some girls/young women of 19, 20, 21 who were emotionally ready for lifelong commitment and parenthood. I don't think many boys of that age are. They tend to be a LOT less mature and a lot less ready for the demands and sacrifices of marriage and parenthood.
And while some women are happy to basically have one, single, lifelong parter and nobody else, I think a lot of guys will get itchy feet if they get older and realize that they are on course to have had only one relationship for their entire lifespan. You can call that sexism or you can call it realism.
In more "traditional" setups where people did marry younger and girls in particular married in their teens, the young men were usually several years older, and frankly there are reasons for that.
A good piece of advice here to the young woman might be, do NOT do anything until the guy has married you. Firstly, this will provide the girl with legal protection if she is planning to do something like complete a degree or vocational training in order to establish a long-term employment plan for herself (and I strongly suggest that she does just that, unless she already has a proper, full-term, long-term job right now). Secondly, it is a pretty good quick-and-dirty test of how committed this boy is. Being presented with a vision of being 40 and never having had a relationship with anyone other than this one woman might concentrate his thoughts awfully quickly!