He’s dating other people
Are you dating someone, even sleeping with someone, and you assume they’re dating other women? Perhaps even sleeping with other women? And you’re not even bothered by it? Well, this doesn’t necessarily have to be jaded. It’s common practice to get to know multiple people while you see which one is a best long-term match. So long as you don’t have the attitude of “Men are pigs—I’m sure he is sleeping around and I just have to accept it” but rather “He is free to feel out his options, as am I,” then you’re just being realistic.