I have a similar situation with my son who is 49 years old. He hasn't seen me or talked to me in many, many years. This was his choice, not mine. I get a text every once in a while but not very often. It's heartbreaking but I've learned to not dwell on it. I did the best I could raising him but he made his own choices/mistakes in life like we all do but he has never forgiven me for abandoning him when he was 23 years old when I went to CA with my late husband.My son who will be 46 in about a week is being uncommunicative with me. It started a few years ago when he was injured and then went through a messy divorce. His life really changed after those events. He has never "remade" a natural relationship with me since. For the past few months he won't respond to text messages ( which is his preferred way of relating). I talked with his sister/ my daughter about him the other day. More bad news...a refrigerator fell on his leg/s. Nothing broke, but injured pretty bad.
I don't know if I should even text him Happy Birthday soon. Is it me not wanting to be ignored again? or will he think of me and want to begin talking again?
I would send him a Birthday text and leave it at that. The choice is his if he wants to pursue it. My blunt advice...move on with your life. I have.