What's this supposed to mean? (Please answer it is short!)?

[Chrome]

So my girlfriend tweeted "crying at (name of a depressing song about suicide) - oh my god".
I then replied by quoting these lyrics from this song, "If it takes you forever I want you to know, that if you fall, stumble down I'll pick you up off the ground". That was supposed to be a message of support and love.

She then posted, on her twitter profile "sigh you just ruined it for me", not as a reply however.
I don't get it. I'm trying to support her and I'm fairly certain that reply was meant for me.
Just today she was quoting something from a letter I wrote her on facebook (she was quoting a compliment I gave her in the letter and saying it had made her day.)

Why is she reacting like this and what should I do? (Please don't tell me to leave the relationship because I think there's hope and I love her).