buddy sour instead of barn sour

I have two horses ( a mare and a gelding) who have been at a boarding stable until recently when I brought them home. My neighbor has 4 geldings and we share a fence line. Every time I take the mare out to work with her she gets so worked up about leaving the pasture, she is almost uncontrollable. She could care less about my gleding, it is the neightbors horses she misses. She was not like this at the boarding stable, she was in a pasture by herself with no horses next to her. How should I work with her to help her get over the fear of leaving them? Any suggestions would be greatly appreciated. My gelding gets upset when she leaves the pasture but when I take him out he is ok and she could care less if he is there or not.

If possible work her hard near the other horses(wherever she is not arguing with you) then ask her to walk away.. I try for more space each time. Go back to where she wants to be and work her butt off. Reward her for leaving them..

You can also do this on the ground if you feel undersaddle is unmanageable for you.. Lunge her at the barn/near the ones she does not want to leave then lead her out. Let her graze a bit when you get her far enough away for the reward to be appreciated. ;) Then lead her back and ask her to go again. Any sass and lunge her again. Make her work, don't just circle her a few times.. You need changes of direction etc in there to be more than mindless circles. :) Don't let her graze or reward her with rest near those horses...