MrsDV a couple of posters responded to me asking whether in all relationships where there's a significant age gap the older partner is abusive, controlling etc with a 'yes'.
You're absolutely entitled to hoik your judgy pants at other peoples' relationships, and I'm equally entitled to disagree with you. I don't know the couple in the OP, and neither do you - so how can you judge whether the age difference is an issue or not? I agree it's unusual, just as the age gap between DH and me is. But DH was always way older than his years and for all you know, the girl in the OP may be too.
It's utterly ridiculous to suggest that all 17/18/19 year olds who enter into age-gap relationships are innocent, naïve victims while the older partner is a predatory abuser. Or to suggest that's what's happening with the relationship in the OP. Of course some age gap relationships will be abusive - just like some same age ones will be.
John yes, a 43 year old having a relationship with a 17 year old is potentially problematic - if both parties want very different things, or haven't had a full and frank discussion about the future. It's a consensual relationship, and both partners are of age. She may get hurt - but so might any of us in a relationship, regardless of age.
When DH and I got together we didn't experience any of the negative, judgy reactions here. I know you'll say 'you don't know what they said behind your back' - luckily our friends aren't as small-minded and judgemental as many posters here seem to be.