The good ones aren't available. Some look promising, but turn out to fail you. Some work out for a while and then just disappear with no explanation. Some you know won't work out long term, but you enjoy them while they last, get everything you can out of it. Some seem like they could work out if they weren't so far away. Some are just too weak to satisfy you. Some ask more from you than you are willing to give. Some are involved with so many other people, they can't give you what you need. Even buying dinner doesn't guarantee you access. Sometimes you'll try one that has worked for you in the past, only to remember why it ended. Some want you to do something you find degrading (like be with them in a McDonalds) and then you just feel dirty afterwards. You can try ones that belong to someone else, but that's a dangerous game. Sometimes a friend will hook you up for a while and it'll be nice, but you know it's not meant to last.
If you find one you can live with, go to bed with at night and find there in the morning, every day, and it still works, you know you've hit the jackpot. And if you do find that kind of loyal stability, for a while you want to hide away with them from the rest of the world, it can be hard to venture outside, separated from that emotional support.
But of course there is a wide world out there full of other people and beautiful sites and koalas and kangaroos (remember, this is Australia), so eventually you have to go exploring and trust that they will still be there waiting for you when you return.