My honey was divoced in 2015. He has a tax debt from 2014 when he and his wife filed married, separetly. Is she responsible for 1/2 this debt?

No because they filed separately she didn't sign that return. 

Thank you!  So that debt is a direct result of his own situation...not their marital situation?  Is being married filing separately just like single filing...HOH or...?

correct ... since he filed his own return only he is responsible for what was on it.