Though, you generally don’t tell that to their face, not in that way, and certainly not when they’re confiding in you about/celebrating finding themselves. That’s simply hurtful, and beyond rude.

You generally won’t go up to your friends on their wedding day, and say the same phrase. You’re more likely to put it as “I’ll miss drinking with you in the back yard, but I’m happy you’re happy”, and not as a seriously-spoken “It’s like watching my friend die!”.