I think you have made a lot of excellent points here and agree with you on your take on most of it. The reason so many "relationships" fail and why so many people here and everywhere feel like "failures" at love and relationships is because they are treating love and relationships like a possession or an object. If you want a tv you can buy a tv , relationships and love are not like that.
The fact is , in my opinion only of course, most of the people claiming to want love and relationships do not want that anyway. I say this for 2 reasons, first most claim to have never had one so I do no tunderstand how it is possible to want something you have never tried or experienced as much as they think they do. I want to try a food to see if i like it but if i have never tried it before I am not at all convinced it will be great. That may sound like an oversimplification, but I do not believe it is as much of a stretch as people will claim it to be. Since there are just as many people miserable and suicidal because they were in love or are in a relationship as there are the same that claim never to have had either, it seems to me that it would be prudent to presume it is not always great.
The second reason I believe that people are not really yearning for love and a relationship is because what they describe as wanting is neither. They describe wanting sex, physical contact, somebody to talk to , somebody to do things with, and "to be happy". Love and relationships , even in the best of them have plenty of sadness , tears, and difficulty. If you cry and are upset about things people say or do that you are not in love with or not in a relationship with then multiply thta feeling by 100x if it is coming from somebody you are in a relationship with. The people claiming to want a relationship or love as the only thing that can bring them happiness and then talking about how much it hurts that people they do not really know blow them off, do not invite them someplace, or want to spend time with somebody else really need to understand all those same things happen between people in love and in relationships as well , it just hurts a lot more. If they are not mentally ready to deal with it from casual acquaintances then they will not find happiness in a relationship because the same things happen only it is far more personal and painful when it comes from somebody you love. If you are upset because a random stranger does not want to dance with you at a club , then how will it feel when it is the person you are in love with does not want to?
The idealistic version of love and relationships people claim to want is pure fantasy and does not exist in my opinion. People that are looking for somebody to "share absolutely everything with" and to "always be understood" and even the more basic and crude "somebody to have sex with whenever I want" might as well stop looking because it does not exist. They take the little snapshots they see of a couple at a party smiling and presume that is what it is like 24/7 when in reality it is sometimes fun and happy and sometimes not. That couple if they have a real relationship and have been together for a long time may well be in the middle of a giant fight but they are used to each other enough to both fake it exceptionally well to try to keep from making the peopel around them uncomfortable about their fight.
As you said so well Syn, if you are looking for it and and need that to to be happy then it is nearly certain that love and a relationship will not in fact make you happy. Until you learn to be at peace without being in a relationship it is really hard to not be too much of a narcissist to ever find a relationship. This is because you are looking for a relationship or love based on what you will get from it and what you want and what you feel like you are missing. It is always about your needs - pure narcissism. Even reading the posts here it is all about what they want to get and what they need - and that is not the foundation of a relationship. A relationship id based on what you can give and share, not what you want from it and need. If a relationship works then it is because both people are trying to give and what they are trying give just happens to be what satisfies the other person. That is what "finding that special someone" is - when what you are giving happens to be what they want both directions. Being upset with somebody for them not wanting something is a little backwards- but it is easy to see how people get upset by somebody that wants too much.
Why do people crave love so much? I am not sure most do - most crave some ideal in their mind based on a fantasy of perfect. That is why most people that are in love say they were not expecting it or looking for it - it just happened- because love and relationships do not come from craving and wanting, they come from offering and giving what somebody else wants. All pure opinion of course.