Advice?😕

My boyfriend & I have been together for over a year and a half. He has never given me any major reason to doubt his love or his loyalty to me, but I am a MAJOR worrier with anxiety & the smallest excuse from him or change of plans, or even slight mood change make my mind race with ideas that he isn't faithful & how I would never be able to find out if he were to cheat.. anyone know how to calm my mind so I can have a healthy relationship..😭 or anyone have similar feelings? Any help is appreciated!💗