He isn't staying hard... is it because of me?

For some reason lately my boyfriend hasn't been staying hard during sex or even cumming during sex for that matter. Idk what it is and it's making me feel like really insecure about my performance like maybe it's my fault. This just started happening like this past week or two and he's NEVER had this happen ever in our relationship. Is it my fault? Is he not attracted to me anymore?