Recognizing that another human being is deserving of love and compassion is not a bad thing at all, nor is having compassion and empathy for someone who was subjected to abuse/hurt/etc.
However, there is harm in the dynamic of codependency. By depending on another person to get what they should be giving to themselves- self love, confidence, coping skills, etc.- it is preventing that person from learning how to obtain these things for themselves. If you should ever leave or something happen to you, your bf would again be deprived of these.
It's like the old saying, don't give someone a fish, teach them how to fish.