What does it feel like to be the toxic one in a relationship?

I’m a 31-year-old woman, and my husband is 36. We’ve been together for over 11 years and married for 4, but we don’t have any children. He truly is the best thing that has ever happened to me, and I love him immensely; I honestly don’t know how I would function without him. He loves me deeply, too, and always stands up for me. He cannot tolerate anyone who disrespects me, whether it’s my colleagues, friends, or even our parents. It feels like it’s always us against the world, which I really appreciate. However, I struggle to match his level of support. I’ve been a people pleaser and an overachiever for most of my life, always wanting to be the nice person and avoiding conflict, even if it means making significant adjustments and compromises on my part. I’ve been trying to change this behavior for a long time, but I find myself falling back into the same patterns. When this happens, we end up fighting, and I feel miserable for both myself and him. Sometimes, I worry that I’m the toxic one in our relationship and that he deserves someone better given all he does for me. I tend to be very sensitive and cry easily, which I dislike about myself. He always comforts me when he sees me upset, even though I often cause the issues. I’m at a loss and feel like I’ll never be the better person that both he and I want me to be. Despite the trouble my tendencies have caused—often allowing people to take advantage of me—I find it challenging to learn from these experiences. There are times when I just want to give up. 😔 Please forgive any mistakes in my English!