Linkin Park - Valentine's Day Lyrics Meaning

I never got suicide out of it. I just thought the "and the ground below grew colder
as they put you down inside" part meant, you know, he's feeling all this pain, and the reality is sinking in, so he just grows cold inside. And at the end, I see him walking down the street, carrying a briefcase or something, on his way to work, all these happy couples around him, and he can't take it, so he runs into an alley, pulls out a knife, and on that last beat, thrusts it toward his heart.