I am going to move this to a debate discussion as it seems best fitting for that section.
I think its that there are some people are not going to find love, Eventually everyone will find love, its more or less that if people go looking for love they won't find. Instead they are meant to be patient and wait for the right person to come along. People who end up miserable are that way because its what they choose in life, they feel they can't be happy so they subconsciously tell themselves they won't and never break free from that way of thinking. Unless something jolts them, then they just continue in a life of depression.
I always thought I would be alone forever, but then I found someone whom I loved so much right under my nose as he was my closest friend and I haven't looked back since.