If you feel like you're playing a part, behaving and responding based on how you think you should rather than authentically, you might want to reassess what's going on. If you're not able to be authentically yourself around your partner, flaws and bad moods and all, it might not be the right relationship for you.
You can tell someone isn't good for you if you're regularly feeling on edge, anxious, insecure, needy, argumentative, jealous, sad, or crying frequently." Perhaps unsurprisingly, being in a relationship with someone who isn't good for you can have quite the impact on your life and self-esteem.