Do you think he just don't care anymore?

my bf and me use to spend a lot of time together but recently all he wants to do is hang out with his no good druggie friends and parties every weekend and never wants to do anything with me. Like tonight our daughter is at her grandma's house and I thought it would be a perfect night for us to do something but instead he wanted to hang out with his friends I'm so tired of it. Why do you think he went from hanging out with me to choosing his friends over me. What should I do? The sad thing is he's 25 but acting like a teenager all over again. It's like he lost interest in me what do you think?