Ok, so she's a little spiteful hey?

:spank:
Wow. Dude, this is serious. You need to stop this “bad habit” or it could become a more permanent mistake (think NOT wanting to marry here). Trust me, that is where you are heading.
Everyone goes through rough patches, sure, but there should be respect for one another. If you don’t have respect then you’ve got a big problem on your hands.
Let me guess.. it went something like this. Your GF says “stop obsessing over that stupid bike!!” You say: (Lie) “I am not obsessing over it and btw it is NOT stupid” she says: “Yes you are!! You care more about that bike than you do about me (Pout).” It escalates and you probably dig yourself deeper by saying she is wrong. Somewhere along the way she gets so infuriated that she feels justified in destroying your prized possession, just for the sport of it!!
Ask yourself would you want her to treat you this way again? (She will). Would you want her to treat your future children this way? (Yes, she would) That would sting pretty bad, methinks.
Consider yourself lucky to have a preview of this behavior now with time to react and rectify. I would say unless your GF is willing to get anger management counseling.. She is a goner.
So there you have more advice from me than you probably want but hey you put it out there, dude.
I feel for ya bro. Good luck.
Ps. White would be my first choice color for a repaint