It's at this time where it's best to say "Well, thats about it, you know it and I know it, lets stop trying," You make the break quick and painless, after all it was coming anyway.
Or, you keep pretending. Pretend everything's fine and dandy. Pretend you're still the best of friends. You draw it out, even though you know in the end it'll hurt more. It'll be harder, feelings will be hurt. You don't talk about it, you hold your breath and you wait, even though you know what you're doing is self destructive.
Nope, just keep your mouth shut. "Listen, we're over, we're so, so over," would just hurt too much to say. So hang around a few more months until the whole thing ends in a blow up. Don't be the mature one and say something. Just stay quiet.
You know the end is inevitable. You know it's right around the corner, but you can't help hanging on, no matter how much more it hurts in the end.
Obviously the first option is much safer, healthy, and probably more sane.
So, knowing all this, I ask myself
Why can't I say anything?