An undivided heartis one that has an intimate, loving and deep relationship with God and no other love comes before this. There is no competition in this heart, God is first.
Emotions by themselves aren't right or wrong, it is what we do with them that make them good or bad. We can work on finding the underlying causes of feelings that effect our life with God. These issues can be the red light on our dashboard telling us to pull over and find the problem.