I'm sorry for your heartbreak and disappointment. Some people fall hard and fast, even over multiple tweets and one date; rejection still hurts. I agree with what some commenters to your story have stated, and that is to learn to be comfortable in your own company and not rely on others to justify your worth. I think Hollywood has done a fabulous job in brainwashing the masses in believing "Rom-Com" movie storylines; where the couple lives happily-ever-after at the end of the movie; which doesn't happen every time in real life and when it doesn't we're left feeling deflated, disappointed and dejected.
I think that many people aren't comfortable being alone with themselves and will chase the 1st person who pays any attention to them (Exhibit A - You) and some people don't possess the courage, to be honest about how they feel the date is going and whether there will be a second date for fear of hurting another person's feelings - or sometimes they need some time to process how the date went before removing the rose-colored glasses and deal with the reality that there wasn't enough there to warrant a second date; i.e.: He decided he wasn't that into you - (Exhibit B - Him) - and we've all been on both sides of these dating scenarios. Harsh, I know, but sometimes honesty can be a cruel beotch. When this happens, take this to heart and remember it truly is "them", and not "you".You did nothing wrong; it just means you weren't meant for him, and he, wasn't meant for you. To quote Maya Angelo, "When someone tells you who they are, believe them the first time." I agree with others on here, in that you probably dodged a bullet and, profound disappointment and heartache with him not following through to communicate as promised. Quick and shortened pain - like ripping a band-aid from a wound that is still sensitive and not fully healed, still hurts like hell but is preferred, versus death and heartache by a 1000 cuts, lies and, deceptions.
However, let me re-tap that vein and re-visit the subject on the fear of being alone; living alone, doing things alone, going on trips alone, you get the idea. Not being comfortable with one's self I think, contributes to the "Butterfly Effect" in relationships; (The "Butterfly Effect" definition: one who goes from one relationship immediately into another, and then onto another because they would rather have short-term or unhealthy relationships than to be alone). For most of us, we enter the world alone, and for some of us, we will exit the same way, and there is nothing sad or wrong about it, it's just a fact in reality. I have witnessed several of my friends go from one unhealthy relationship to another with minimal alone time in between; I mean I've had dental crowns that took longer to make, and yet they wonder why they can't find "the one" - they chose to recognize the "red-flag" signs in the relationship and trudge forward in ignorant albeit fake bliss, then to god-forbid, go it alone. Society has plagued itself with qualifying the self-worth of an individual by whether they have paired up with someone or not. As a single person myself, I had many discussions where I've had to educate and correct their misconceptions and generalized assumptions of single people. Q: Wouldn't you like to be in a relationship? A. Sure, with the right person and I'm not going to settle just so that I can say that I'm in a relationship.
In closing, please take a moment to breathe, take a long hard look in the mirror and realize that you're perfect just the way you are and that someday, someone will come along who will want to be with you, have a second date, enter into a relationship with you or even marry you. However, if that day or man doesn't come along, it doesn't mean that you stop living, or that there is something inherently wrong with you, it just means that the person whose shadow crosses your path isn't meant to be your human. In the meantime work on being your own best friend and constantly work towards improving on yourself in whatever endeavors you entertain.
I wish you the best in this life and hope that you'll see yourself as the gift that you are.