I feel the same way, you are really not alone. I get really jealous whenever I see another one of my friends somehow find someone who wants to be with them. I feel like at the beginning of every new “fling” I get too excited about the potential of it turning into something serious and overlook all the persons faults and signs that they are not the one, which makes me more heartbroken in the end. What I am going to try to do from now on is to accept the relationship for how it is in the moment and not idealize the person. All we can do is try over and over again. People say dating is a numbers game, go out with as many people as you can, have fun and try not to take it too seriously. I have faith that the right person will be worth all the past heartbreak.