Well if it was either of my dc I would not be happy about it at all, and would worry they were missing out on certain life experiences that occur at that age compared to an older partner who would most likely be more settled and at a different stage in their life. However, there’s not much you can do about it. Age gap relationships can be a real mixed bag so it’s not all doom or gloom but keep an eye out for her.
My dh’s uncle got together with his wife when he was 20 yo and she was 36 yo. She had two children already and told him she wouldn’t be having any more. His family were livid about the relationship, interfered and tried to get them to break up, but he stuck with her. Due to the fuss the family made they ended up emigrating to the USA. They’ve been together at least 45 years now and are still
going strong…although no one sees them much because they still live in the US. They are very happy although the uncle is sad he never had kids.
My friend’s brother got with a 24 yo when he was 40 yo. The age difference might not have been an issue if he was reasonable man, however, he’s controlling and he hated her going out with her friends. He basically wanted a young hot wife who did as she was told and was a homebody. He spent his 20s out drinking with friends and having fun, but begrudges her the same experiences. She had a large group of close friend and over the last 8 years he has created no end of issues between her and her friends and now none of them talk to her. She’s completely on her own with just him.
A close friend of mine got together with a 45 yo when she was 19 yo (they’re now late 50s and 30s). They are one of the best couples I know. They’re totally devoted to each other, have such a loving healthy relationship with strong communication, and spend their time having fun and laughing together. It shouldn’t work but it really does.
So like I say, it doesn’t have to be the worse thing in the world, but I’d also keep an eye on her at a distance. You’ll be able to spot red flags better than she can.