My boyfriend please help

Okay I have been with my boyfriend for almost two years now and o don't understand I'm so afraid I'm gunna lose him the thought kills me I'm afraid I'll fall out of love with him or something I love home to death and I always wanna be with him he's the best guy ever and I love being with him I just don't understand why I dobut my feelings for or feel like it could end I don't want it to ou have loved him for long time and have wanted to be with him forever he is my first boyfriend and I love him I don't wanna break up with him and I don't wanna lose him  why do I feel this way?