Well, take it as a lesson. If you want to give a relationship the best chance you can at succeeding, you have to be honest about how you're feeling and what your needs are even when it's hard and awkward and you're scared to rock the boat. I understand being worried that the relationship doesn't have a solid foundation yet and not wanting to scare him off, but a solid foundation is built on honesty and open communication. It doesn't just happen with time, you have to do some scary uncomfortable shit to make it happen. If you're looking around for someone better while he thinks you're exclusive, not only will that hurt him and his ability to feel secure with you, but it will also hurt your own sense of security and trust in him (or any partner, for that matter)--because if you're not really all the way in it, you're gonna be seeing his behavior through that lens too. You're gonna stay looking for signs from him that he isn't really in it either, because that's the mindset you know best. That can become a self-perpetuating cycle really quickly, with both of you sensing distance in the other and pulling away further out of fear.

You mentioned wanting a deeper connection with this person, and really as a general rule, deep connections come with deep honesty. They're a package deal. Sometimes the connection seems to come first and make the honesty easier, and I think that's sometimes what we subconsciously expect from the "right" partner, but I think most often the honesty has to come first. And that shit can be seriously scary--scarier for some folks than others, to be sure. But it can really be worth it, and frankly if you're not willing to be honest you're gonna shoot yourself in the foot every time.

Anyway, from one person who's deeply terrified of being vulnerable in relationships to a potential other, lol, I really wish you the best. Hope you learn a lot from this.