Relationships can definitely put a dent in your sense of self and identity.
If you tend to be anxious in your relationships your focus is directed to fear of the relationship ending. You are vigilant (albeit subconsciously) and on the lookout for proof that something is wrong. You can click the link above to learn more about anxiousness in relationships. If this is you, you are likely over-giving of your time, energy, and money to make sure the relationship is stable.
This type of relationship is exhausting and many lose themselves in the relationship and don’t recognize who they have become
A narcissistic relationship is probably the worst type of relationship. It is completely damaging to your identity and sense of self. It chips away at your self-esteem, self-worth, creates massive mistrust in your ability to make decisions, to think logically and to trust yourself. You question everything.