feeling sad about mom

I recently noticed something. I have a difficult relationship with my mom, and always have. I see a lot of people around me having loving relationships with their mom, and I always think to myself “i wish I could have that”.
I have done a lot of work on my relationship with my mother, but unfortunately she is mentally unwell and I know that we wont get to that point. I have worked on my beliefs, expectations etc.
I can’t help but feel a sense of sadness like “I wish I had that bond with my mom”
I have the best mom in law in the world, and have a mother-daughter bond with her. But I still feel this terrible sadness whenever I think about my mom, and our situation.