What a heartwarming story.
What if they did end up having the kids, and like a lot of young single parents, were not able to do a good job raising them? There are enough degenerates out there made that way by parents who were not ready to raise them.
That reminds me of a couple of people I went to school with. The girl was 15, the guy was 18. She ended up getting pregnant, he was bashing her and they were both abusing drugs and alcohol. They split up and the grandparents brought up the daughter. I got an update of the people I went to school with 3 years ago. The guy has Hep C, he's probably deceased now, and the girl became a grandma at the age of 38. The great-grandparents are helping bring up the child as the boyfriend didn't stick around.
I feel it's my duty to protect my children so there is no way I would allow my children to date people who are old enough to drink alcohol and go to night clubs while they are still studying at school. Who needs all the complexity of love at such a young age? Be a kid for as long as you can IMO!