This is a tricky influence to deal with, but one that could teach both of you a lot about yourselves as well as about the way that you function as a couple. Emotional security is an issue between you; your lover doesn't always feel entirely emotionally fulfilled, and responds by withdrawing, possibly repressing emotions to avoid the difficult work of dealing with them. This relationship also might bring up past issues for them concerning their parents, especially their father.
As a kid, they probably had to compromise themselves and what they wanted out of life in order to serve their father or their parents; but now they're an adult, and they don't want that same parental influence in their romantic relationships! That makes sense, but neither of you should overlook this opportunity for growth and understanding. It might be that this aspect between you encourages your lover to look closely at themselves, their life and their emotions, and to deal with issues long ignored. Compromise, after all, is essential to any relationship -- between parents and children or between two lovers trying to forge a relationship as equals. Your lover's depression and feelings of being restricted by you in this relationship are a natural response to this energy between you, but it doesn't have to be the only response. They could take this as a learning experience, and find out where they are actually holding themselves back.