Your crush is everything you want in a guy. He's cute, he's funny, he's smart...and he's your best friend! Aah! Add in that minor detail about him being your BFF, and you've either got a recipe for disaster or a match made in heaven—it's a toss-up when dating your friend.
It's hard not to have a crush on your best friend and want to start dating your friend. He's obviously fun to be with—you wouldn't hang out with him if he weren't. Plus, you guys have the same interests and can be comfortable around each other. Before you run to his house, screaming your vow of undying love for him through the streets, you have to decide if this crush is for real and if you're ready to put your friendship on the line.
If your BFF has a girlfriend, get over him NOW and any thoughts of dating your friend. Don't try to interfere with their relationship. Your best friend is not dumb. He'll realize what you're doing and probably get angry with you. And there goes your friendship. It's not fair to your friend or his girlfriend to try to break them up just so you can try to start dating your friend.
You'll have to wait until nature takes its course and the two break up on their own. Wait until your friend is off the rebound and then make your move to try to start dating your friend. However, they may never break up, so be realistic and move on.
If your friend is single, make sure this crush is the real thing before you profess your love. Why do you think you two can be more than friends? If it's because you recently broke up with someone, and he's been there for you through the hard times, it's probably not a good idea to make your move to start dating your friend.
Maybe you think he's been especially flirty with you lately. Flirtation is hard to gauge. You might think he's super flirty because you're looking for any kind of sign that he feels the same feelings for you as you do for him. You might be reading him all wrong, so be careful.
If you're sure your feelings for him are real, go for it and try dating your friend. Don't tell him when you're around other people. Tell him when you're somewhere quiet with little distractions. Be honest, but don't go on and on for hours about how you've been in love with him since the two of you were in diapers. That will scare him away. Just say, "I like you more than a friend and hope we can go out sometime. If you don't feel the same for me, that's OK. I'd like to remain friends with you."
He might say no. You will be crushed and sad, but you'll get over not dating your friend eventually. If he says no, don't ask him why. That's like asking him to rip your heart into tiny little pieces after it's already been broken. Be respectful and don't badger him.
Remember, even just confessing your feelings to him may make your friendship really strange. He might not want to hang out with you as much as before. He might be distant for a little while. Your relationship could return to normal or it could change forever. That's another thing you have to take into consideration when you think about dating your friend.
If he says yes, good for you and good luck!