Do you think he’d be uncomfortable or angry with you if you date his sister? Remember — this is the guy that you’ve been bouncing off dating questions for years, as well as the only other person on Earth who knows anything about your sex life, besides the girls that were involved.
He might simply know too much about you and your predilections to not feel at least a little uneasy at the thought of you dating his sister.
But lots of guys have friends that they know are really nice and would be really happy if they hooked up with their sister.
My brother's lifelong best friend is a really great guy and we have a lot in common.
If yes, then this indicates that her brother (read, your friend) might disapprove of this relationship. In fact, you should drop the very idea of dating a friend’s sister.
Even your friend may approve of her joining your group.
However, if you’re interested in an intimate relationship, better watch your step. If it doesn’t work, you may have to live with a lot of guilt and humiliation.
You must be clear about your intentions before you even think about doing such a thing. If it doesn’t work, you are gonna get entangled in the biggest mess of your life!
I would suggest dropping the idea of dating a friend’s sister altogether.