You say you're increasingly "attached" to your best friend's fiance. Although you sound like a barnacle, I assume you meant to write, "attracted." But your slip of the fingers is illuminating. You need to quietly start unattaching yourself from the boyfriend of someone else. Imagine that you go ahed and get your feelings off your chest: "Diane, Nick, I just wanted both of you to know that I fantasize about Nick constantly, and now that you're out of sight, Diane, I can't help but imagine myself stepping up and becoming Nick's fiance." How's that going to go? Since you work with Nick and volunteer with him, sure, you can't help but spend time with him. What you can do, however, is start building your own network of friends. Surely you recognize that the Three Musketeers are going to have to disband someday. (You'd probably like Diane to be the one to drop out.) Nick has given you no sign that he's the slightest bit romantically or sexually interested in you. That's good news. Trying to move in on your best friend's fiance is a plot development best left for the next Ann Hathaway movie.