I feel the same, and ashamed to admit it. I love the bones of DH (no DCs), and whilst I don’t have many close friends now, I have in the past, and have felt fiercely about them too, so I know I’m capable of it. But when it comes to DM (DF died a long time ago), I feel kind of emotionless. I speak to her regularly, I’m kind and thoughtful towards her, as she is to me, and on a surface level our relationship is fine, now.
But as a child / teen, she was just, well, not a very good mother. Looking back I strongly suspect some kind of depression and / or other undiagnosed MH issues. She was unpredictable, quick to lose her temper, and full of resentment, I never felt safe, or loved, or special, and I could never work out why she wasn’t like other mothers, and why she didn’t actually seem to like me, or like being a mum. As an adult, I can see rationally that she had a number of traumatic incidents happen to her that no doubt shaped her, but although I can acknowledge that it and allow for it doesn’t ‘fix’ the lack of bond/attachment that should have developed between us at an early age but clearly didn’t.
I feel terrible about it, as now she is genuinely loving and caring (she’s like an entirely different person), getting older and needier, and she wants a lot more from me emotionally than I can give her - I struggle with visits, and with physical affection and declarations of love. It’s much easier for me to maintain a good relationship on the phone, and we live at opposite ends of the country – I’ve not seen her in a few years which I know upsets her a lot, but is better for me.
She won’t discuss the past, and just says things like ‘I made mistakes let’s leave it at that, but you turned out ok didn’t you’. I just don’t think she is capable of reflecting on the past and how that has affected me / our bond on a really fundamental level. It’s sad, but I keep having to remind myself it’s not my fault, and at this stage it cannot be actually fixed. I have considered counselling, but it would cost me a fortune and in the end, it wouldn't really benefit me, as I'm actually quite happy with the way things are, it's DM that isn't. All I can do is be kind and supportive, but with boundaries and in a way that protects my own MH.