I too detached from Mother in my early twenties when I was myself was going through a divorce and needed her. She liked my ex-husband and felt sorry for him and told him where I was living. He was a wife-beater, but he was such a Clark Gable smooth talker and she fell into his "web". So I didn't talk to her for about a year. But then, tragedy occurred. I got a call from Aunt that my Mom had breast cancer and had weeks to live. I visited her as often as I could but I was close to having 2nd son and she died when I was in hospital with son. I held a grudge and I regret it now many many years later.
I think sometimes in early twenties we hold grudges with our parents and we need time to sort it all out if we are justified or not in our feelings. At the time, I felt justified. I always thought she would be around and didn't know our time would be cut short. She died when I was 24 and she was 49. I wish I had been emotionally mature enough to know how to have handled the situation better, not rejecting her totally, but able to keep communication ongoing, but at a distance. My Mother and Father put my sister in an orphanage after having lost our two brothers as infants which destroyed them and their marriage. So at an early age I saw things as "rejection" and anytime someone was going to hurt me, or hurt me, I rejected them first before they could reject me. I have healed from that "way of handling people". But it took many years to see what I was doing.
My daughter went through a stage of "why didn't you do more arts and crafts with me", why didn't you do this or that, etc. I told her I had 3 children, worked full-time, one child being special needs and I did the best I could. I apologized. Fast forward years later, we are very close and have a great relationship. She had to sort out her feelings- I gave her time to do so. In early twenties I think folks are very "me" centered and when they get to their 30's and have had children, experience life situations, ups and downs, curve balls that life throws us, our kids mature and come back to us.
I agree with others, enjoy the limited time, love those who love you and want to be with you, focus on those folks. Be there if she wants to heal from her hurts and wounds. It all takes time, but live every day to the fullest. Find Joy in every day.