You shouldn’t wait for him.
He broke up with you because he thinks that he is missing out on better dating opportunities.
Even though he told you that he isn’t really opening himself up to others in a romantic way for now, that wasn’t entirely honest.
In breaking up with you, he is freeing himself emotionally, as well as his conscience.
This way, if he were to meet someone else that grabbed his romantic attention, he won’t feel bad about talking to her and would also have the emotional availability to develop feelings for her.
He told you that he would feel it if he lost you and has continued to talk to you everyday at long lengths because he is keeping you as his insurance policy.
He hopes that you will maintain your feelings for him so that he will always have you as a last option to come back to if no one else grabs his romantic attention.
Being that you like this guy romantically, as opposed to only liking him on a platonic level, if you were to wait for him and still keep talking to him, you will only develop deeper feelings for him, while he is free to do what he wants with his emotions and entertain talking to other girls.
You would be operating on his clock of which there would be no guarantee that you will end up being with him as a committed couple.
Yes, you should leave.
No, you should not stay closed off to other guys.
Yes, you should be open-minded.
If you wait on him, you will miss out on other opportunities with other guys who may be a lot more clearheaded on what they want and how they feel.
You shouldn’t be anyone’s insurance policy. If you are, that claim may never come due.