It's difficult for both of you to fully be yourselves in this relationship, because there is so much deep-rooted conflict between you two. Even when you had only just met, you felt the effects of old, unconscious wounds rearing their heads. You may feel as if you've come to this relationship for a reason -- that there must be some meaning in why you're going through such pain together.
You both have some painful deep-past issues that have come to the fore through your interaction. Transformation is needed. But your partner's evolution as an individual is in direct conflict with your own individuality, or your idea of who you are. Resentments can build up as criticisms lead to tiffs, tiffs erupt into arguments and then intensify into full-on, angry disagreements. You're two different people; that's unavoidable. But this particular relationship can't serve either of you as individuals unless you make the necessary changes. You may find that over time, you've begun to grate on one another's nerves; the smallest disappointments seem huge, the most minor infractions suddenly enormous. Everything is loaded with emotional baggage. Your lover, especially, makes demands on you regarding your behavior, even your feelings -- which can't and shouldn't be controlled by another person. This a very difficult aspect to work with, and it requires much patience and compromise on both your parts.