This is endemic of your general outlook on life, which is in turn typified by your screenname.
Perfectionism is a big problem in our community.
The way it is manifesting here is that you think there is one perfect person for you and if you marry her it will be bliss and otherwise it will be misery. That is not true. But I don’t think I will be able to convince you of that, and even if I do it will not help in the other parts of your life. Dr. Ben Sorotzkin talks about this in some of his audio and text available free on his website.