I am 28 years old and my sister is 20 years old. She is talking to a guy who is 31 years old.
Should I let her date the guy or should I stop her?
From talking to him when she told me about him I got angry cause I couldn't understand why she was talking a guy who is way older than she is. I tried talking her out of it but that didn't work. I love my sister and I just don't want anyone to hurt her that why I'm so skeptical.
No, you generally shouldn't prevent an adult from speaking to another adult.
No, you can't "let" an adult relative date someone else. This is not a right of yours, and also not something you can manage to do if you try.
If you don't want anyone to hurt her, start with yourself. Another man she talks to might hurt her, but an overprotective relative who meddles with her social life will hurt her.
EDIT: The above does not apply if the other person has a mental disability and you are their legal guardian, in which case the answer becomes more complicated and depends on specifics.
There exist a fair amount of women who are into older men. I think the general populace consider the women who do have these things to have some sort of daddy issue, that they want to date their father in some sort of Electra complex.
Older men often have settled into a good career, they earn more money and are generally more successful. It is only natural that a woman is going to be interested in a man that they think could provide well for a family, no woman wants to marry into poverty.
Older men also often have a richness to their lives that many women would find appealing, they have a confidence that many men only develop when they settle into there thirties. All of this is very natural and not all that anti-social.
The bigger issue I see is why you are have an issue with who your sister dates at all. She is not a teenager anymore, why are you treating her like one?
Another question is why would you think a thirty year old man is more likely to hurt your sister than a 23 year-old?
Many women like the confidence and security older men have. Best thing is to withhold judgement and meet the guy. After meeting him you'll probably be able to smell bullsh**t if it's there, at which point you can calmly make some arguments. Or, maybe he's an upstanding guy. Point is, age alone isn't enough info. It's a big age difference for sure, but you'll make stronger arguments based on character than just on age.
11 years is not a father figure difference. Unless you want her to stop speaking to you, stop trying to run her life. If you have concerns, express them, then butt out.
Without knowing your sister and your situation, I can only go on a little bit of guess work but here's my take on it.
You say about you letting your sister date this man. This, to me, suggests that there's no father figure in the picture and probably hasn't been for a while.
Her talking to an older man isn't really all that unexpected in this case. She's looking (whether consciously or not) for a partner who can also be a father fogire.
