My best friend has been acting distant since being in a relationship, what Can I do?

My best friend of 4 years, we used to talk every day, text everyday and talk about everything with each other. He lives in New York and I live in Texas so we communicate through phone. I left for Asia for 6 months and whenever I text him, he responds to me every 3-4 weeks later. He got into a relationship this Christmas. He and I used to have the friendship where we talked at least every day and if not at least once a week. But now I feel ignored by my best friend. I don’t love him or have feelings for him. I just miss my best friend.