New relationship- scared of it ending.

I’m in a new relationship, seeing each other for about 3 months, official almost a month, and i cannot get over the anxious thought of our relationship ending somehow. Nothing is wrong at all; I’m head over heels for him and he is for me. But i just have that unsettling thought in my stomach and i don’t know how to get rid of it. He’s the type of guy I’ve been searching for for years and I’m scared of him leaving one day