You are not going to do well in your marriage or relationship if you don't like your part. It's like the predicament of an actor in a play who can't get into the role that s/he plays and therefore doesn't play it well. Odd then that many of us who don't really don't like ourselves in the marital role that we are playing, do nothing but complain about it and then like ourselves even less.
There are any number of reasons why people don't like themselves in their marriage or relationship role: They are submissive when they don't want to be, nagging when they hate nagging, long suffering in silence, when what they want is a strong, take-charge role.
They are cautious and careful when they want to be spontaneous and take chances. They are slaves to work when they desperately want to play and cold and distant when their impulse - and the role they want to play - is warm and affectionate.
When people don't like themselves in their roles, not only do they do them poorly, but if things don't improve, they almost certainly leave the relationship. They don't necessarily pack up and move out. But they almost certainly withdraw in favor of roles where they like themselves much better. They pour their energy into friendships with friends who like them and encourage them to be themselves. If they are good mothers and fathers then, failing at the marriage, they strive to become even better parents. If they do well at their trade or profession, they stay at work as many hours as possible.
If "I don't like myself in this relationship" is your problem as well, there are steps you can take. You can literally resign from the play (get divorced). You can do what you may already be doing: play your distasteful role as lightly and minimally as possible, while investing yourself wholeheartedly elsewhere.
And a more creative option: You can approach your partner to see if your partner also doesn't like the role that s/he plays in this marriage or relationship. A tip: Don't go to your partner full of blame. Remember: You don't like yourself in the blaming role. Besides, it isn't your partner's fault that you play the role you do. You could quit, you know.
Tell your partner without blame that you simply don't like yourself in the role or roles that you play in the relationship. (E.g., "I hate that I am distant and cold with you, when what I want is to be close and affectionate.") Then find out if - surprise - your partner also doesn't like the roles in which s/he finds herself and see if together you can make changes so that both of you can get to like yourselves more - and succeed better as partners.
Please comment: Describe a role that you sometimes (often?) play in your relationship that you don't like. What role would you like instead?