Most Helpful Guy
I think Age/2+7 is a good general rule. I think it's kind of creepy when someone is partnered with someone who is old enough to be their parent, but it's not my place to judge... usually.
The worst case I witnessed personally was when an 18-year-old girl eloped with the 30-something manager of the Domino's Pizza where she worked. On her eighteenth birthday, this greaseball and his three roommates showed up at her house when her parents were out, moved her and her furniture out of the house. No announcement, no discussion.
Her parents came home that day to a ransacked house, a missing daughter, and a note saying she had gotten married and moved out.
Most Helpful Girl
Adults are free to decide if they want to date each other, but I'll be honest: I tend to skeptical of their relationship and judge the older person negatively, particularly if the younger person is only in their late teens/early twenties.
I'm almost 30, and I can see a huge difference in maturity in myself compared to when I was 21, as well as in people I meet who are around that age.
I tend to assume that the older person is interested in the younger person for shallow/pervy reasons (like, they're dating them just for their appearance or because they fetish for people they perceive as young, innocent, naive, inexperienced) and/or they want to date someone so young because they see them as easier to manipulate, and/or they're really immature themselves.
Obviously there are people who can have a genuine and healthy relationship with a large age gap, but I'm still skeptical because of the number of unhealthy relationships I've seen and the way I see a lot of (particularly) older men talk about young women (it's gross), and because there *is* a power imbalance present when there's a big gap in age/life experience.