I think you can learn from this challenge. You have wondered why you have had people let you down and not give you a reason right? You have talked about how that had a negative affect on your self esteem. Well, now you know that even though this other guy was nice and you had a lot in common, you just did not click and it did not mean there was something wrong with him. Maybe the feeling of guilt is more about not letting him know or giving him the courtesy of having feedback where you could feel better about moving forward and meeting others where you may make a better connection.