@Eckhart and anyone else, this is really interesting:
We are all responsible for our individual wellbeing, and making sure our needs are met.
I'm in a great relationship, and also had great times on my own (I'm an introvert and an only child, so regard any presence in my home over 2 hours, including my partner, with mild panic)
I've also been very sad on my own, and very sad in previous shitstorm relationships.
I'm fortunate that I have some lovely friends, some partnered up, some not, and they are vital to me.
However, my interpretation of your interpretation of relationships (of any kind) is that they are like a bank account. You put money (goodwill and kindness) in, you can draw it out later. The relationship is hence a reliable indication of your worth as a person and the amount of work you have invested.
This is absolutely-tippity-top-1000% not my experience.
Just because you invested time and love in someone, doesn't mean it will be returned when you need it. Not because people are mean or selfish. But life is complicated. They might not have the energy/time when you need it given back to you
Moreover - and this is scary but also fascinating - everyone sees the world differently. You can't guarantee that your meaning behind an act of kindness, a visit, a hanging-out, time spent with them, is the same as their interpretation. I'm really happy with my friends. But I'm aware that some people, whom I think I am very close to, might not see it that way. Conversely, I am aware that, in the past, some people thought I thought I was close to them, and I'm not.
Not because they aren't good enough, or I'm some dreadful manipulative menace. Just because the chemistry isn't there.
I haven't conveyed this very well so I hope this makes sense. But I'm passionately in disagreement that kindness to X and Y means that X and Y will be there for you when you need them.
Because, however fantastic and decent X and Y are, life is complicated.
And @Separatedandabitsad, my situation is different, as I have a partner, but there are strong commonalities in my experience, and I hear you.