@Jeanmiwan : Deer also resent those who break trades. Maybe you broke enough trades to turn them hostile despite holding alliances. Also, when you attack or support an attack against a race you have treaties with, you will automatically break those treaties and Deer will resent you for that.
Game makers, please stop adding "mind bending" to the description of your game eveytime you add a little twist.
And don't add the "puzzle" tag when your levels are so linear that they involve no reflexion at all.