Hi Beeva, welcome
Re: ". Friends say just "get on with your life" but it's always there hurting." They are right more on that later.
Re: "I truly cannot see what I have done to deserve the way she now treats me. I feel that she is punishing me!" You likely didn't do anything that deserves such treatment.
Re: "usually just a text message." You might be one of the lucky ones
Although my daughter is much younger at 22yo there is a common streak there. I've gone over and over in my mind of anything I've done to upset her. The fact that I still provided for her with not a cent of arrears in child support doesn't matter to a child of ours for example. They don't look at dads that avoid paying it to a reasonable level. At 14yo I paid $14,000 above my child support so my daughter could get her jaw and teeth realigned. At 20yo she became a Facebook friend and she thanked me then for her jaw operations then a few weeks later defriended me for no apparent reason. So like you I was again thrown on the rubbish dump.
You will have to decide yourself what you want to do but for me constant disruption, minimal communication, likely coercion from her mother, no real effort and so on was just too much for me. I told her once- "I cannot be a grandfather to any children you have unless you want to be a daughter to me". Reason being that if I became a grandfather and was introduced to them I run a serious risk of her stopping me from seeing them. And the hurt continues. So what was my final decision?
I needed to come to terms with it all and make a decision. I decided that as she has a car and license I will no longer drive one kilometre to see her. I'm 2 hours away from her. She can come and talk. I don't want her accompanied by anyone eg boyfriend, children. She has a narrow window of possibility to create a relationship with me, so narrow I'd say its highly unlikely due to her stubbornness.
You must protect yourself from anyone that is unreasonable and hurtful.
Mental comfort in these situations comes often from making your own comfort zone. Your daughter has chosen not to tell you the reasons, that she is "dealing with it" tells me there is some issues she needs to work through.. But if you don't know what they are you cannot help.
"move on with your life". Easy to say, hard to do. Erect the fence she needs to jump to be in YOUR life., the fence of reason and compassion.