Seriously grumpy mare (not me for once)

[tubby1]

I have a 6 yr old ish mare ( chestnut ) Normally she is a sweetheart in the stable . 2 weeks ago a new gelding moved in beside her and she hates him. I thought she would settle but she keeps trying to attack him thank goodness for the bars between them. Tonight when I went up to feed she was vile lunging at him. Normally this settles after she has her feed but tonight it didn't stop. I felt quite uncomfortable changing her rug as she was trying to kick and she was generally being a total plonker !!!!! she has also started to buck when I ride her but don't know if this is related.
Could she be in season there are no other signs?
She is my first horse so I'm just curious if anyone else's horse has taken a dislike to a stable mate.

 

[StarlightMagic]

Oh yes when I first had my old mare she was originally in a stable with a screwed in partition and had to be moved because she kept knocking it diagonally, then moved to another stable where she had to have duvets and rugs over the bars in between stables so she didnt beat the hell out of the partition She never changed behaviour ridden though

 

[be positive]

I had a mare that hated being constantly looked at in a barn she just got more stressed and was not happy until she was moved to a closed box, can you either put boards up or move her somewhere else as she may just get worse.