I dont like spending time with my bff

I know my bff since 7th grade. we only became bffs in eighth grade. I really liked her personality and humor. We did everything together and other kids were really jealous of our friendship. Whenever there is a pair work, almost all teachers put us into the same group. Then when we came in 9th grade, I didnt like spending too much time with her. Later she got a bf. Then onwards all she talked about was her bf. I got annoyed and i slowly tried to change the topic. But again she started talking about him. later in 10th, I started hanging out with another girl. So my bff started hanging out with another girl. but we didnt break our friendship or anything but inside we both knew that we are not bffs anymore. I kind of feel guilty that im avoiding her and hanging out with my other friends. I dont know why but sometimes im jealous of her. Shes been cracking lame jokes and acts all kiddish. I feel like i dont know her anymore. Is this normal?