The Love of My Life..

Have you ladies ever sometimes second guess a relationship ? Idk, my boyfriend I have have been dating for almost 4 years and every now and again I wonder what would happened if we broke up. But lately, he hasn't been as lovey as he has been. He's had moments, but I feel like we barely talk or interact due to our schedules. We moved in together with my best friend 4 months ago. He has the tendency to think " Oh I've won her, now I can stop trying". And I've tried talking to him about it but he doesn't think he does that. But when I think about my life without him, I get so anxious and sad. I don't want to break up but I guess I wanna know if anyone else has experienced thinking about it?