It’s okay to date your friend’s sister as long as you handle the situation well. Most guys are very possessive of their sisters and if you are the type that likes to flirt and if this friend of yours knows about it then you are a dead duck! Obviously you will have to be a bit manipulative to keep calm and peace between friend and sister.

The first thing you should know is that, guys, no matter how flirtatious they are, will always want their sisters to settle down with guys who have never had a girl in their lives. As impractical as it may seem, it is the truth. So your chances will initially be slim as I’m sure you don’t belong in that group. Don’t tell your friend that you are in love with his sister. If you’re flirting with other girls in the meantime, don’t tell her that. Start doing something nice for the friend. Remember that the friend knows you well, so please don’t take a sixty-degree turn and be overtly nice. Change gradually and stop talking about girls as much as possible. Tell your friend that your interest has shifted from girls to something else, something much more serious and mature.

Get a little boring and uninteresting, but not stupid. Hang out with your friend as much as possible and do something for him that will put him in debt to you. He begins to meet his sister in front of him, never allowing him the feeling that you like him. Treat her in an informal but friendly way. Don’t flirt with her when her brother isn’t around. She should be able to trust you. Once the groundwork has been laid and you’ve met several times, you can ask her out, but of course with your friend’s permission. He may or may not grant you permission; this will totally depend on how you present it. Tell her you’re only taking her to lunch. This is a very safe option, as your friend will know that you cannot exercise with the girl in broad daylight at a restaurant. Convince the girl to go out with you too.

Once you get her to lunch, keep repeating the process until the sibling relaxes. At this point, I suppose you would have enchanted the girl enough to want to date you. Then move on to the movies, this is a slightly more dangerous situation for brother, as once the lights go out, anything can happen between the two of you. Once you have repeated this process, take her out to dinner. But always remember to leave it at home after that.

It may sound tedious, but this is the best way to handle a sibling. At the end of, say, two months, you will not only have a girl to love and sleep with, but also a brother and a friend.