Have you ever felt like you don't deserve the person you're with?

No. Relationship-wise, I base whether or not I deserve my partner on if she wants to be with me or not. In addition, I base my deservedness on if I like her, if she caters to my tastes and preferences, and if we can have a healthy relationship. Considering that my partner wants to be with me, I love her, she's y, and our relationship is great to the point that we've been together for a year and never had a single argument, I accept as truth that I deserve my girlfriend.