Sometimes we can't help who we have little crushes on. It's pretty common, especially if the guy is especially nice, funny, or good-looking, and it's someone that you see regularly...like, say, a sister's boyfriend.

The important thing is how you handle the crush. Obviously, you're not going to try to steal your sister's boyfriend away from her, right? That would definitely be inappropriate. Decide from the very beginning that, whatever you think you feel, he is strictly off limits. Thoughts are okay (maybe not ideal, but also unavoidable) whereas actions are NOT okay.

I've been there and done that, and the good news is that crushes, when not acted upon, usually fade after a little while. So don't be ashamed - just keep reminding yourself that he's off limits - and keep an eye out for someone who is just as cute but available for flirting. Good luck!

There's nothing wrong having a crush on someone. It's a normal feeling and we cannot control that. However, you should know your limitations. For your case, you must keep in your mind that your crush is your sister's boyfriend. Having said that, it's a no no to flirt with him. You could treat him like a friend or a brother and by doing that, you are already respecting your sister. Always remember that your love with your sister is bigger than the infatuation that you're feeling on her boyfriend.

I don't think it would be better idea to crush on him. Rather to find out someone else.