It was good for a long time

Dating your friend's older sister

And forget about

But realize that if she hates the idea and you go for it anyway, it could end up messing up your friendship. One date with this girl could have a huge effect on your friendship. Your relationship with her brother could put a strain on her relationship with you.

She just also happens to be my friends sister, not sure how much that complicates an already awkward dynamic. It might be less terrible if you carefully read this ten-step guide.

Dating his sister may be one of the things that would be crossing that line. If we wanna hook up or date that is our buisness. By all means, engage her in discussion about it if she brings it up. And this is an even worse habit in this situation.

Do some sort of vaguely excusable

Not only do you induce chances of altering a perfectly cemented friendship, you also land up treading an established comfort zone. He is more mature than any guy my age or older that I have ever been involved with. You can explore a relationship with a friend's sister, but don't be deceptive about it. Or he could be totally cool with it.

Do some sort of vaguely excusable professional coffee. And forget about talking to her about your relationship. This is an unhealthy thing to do in general, and doubly so in this case.

And this can be hard to figure out, as a sufficient level of arousal can make every person of every gender think their potential lover is the most interesting person in the world. If she gives you her blessing and you two go for it, make sure you keep your relationship and friendship as separate as you can. She is her own person and so am I. Let her know you really want her approval and you really want to know exactly how she feels about the whole thing. Often, this is not true, which is why the first date is a valuable no-stakes screening procedure.