In your opionon,

Is it better to have loved and lost, or never loved at all (as the old idiom goes.)?

never loved at all b/c then you wont feel the pain when you lose it.

loved and lost
not every relationship is going to work out obviously
but every time they dont you get one step closer to finding your perfect partner
and youll never find them if you dont try!

you have to have a few "bad" relationships so you can find out what exactly you want and don't want in your soul mate.

loved and lost. I´m so sure of this, since if you don´t do anything than you´ll regret and it will make you so terribly mad at yourself. While if you have loved, but lost, t be in emotional pain. But I honestly I believe that dealing with that pain will be a part of growing and learning more about yourself, which is something very valuable when it comes to moving on.

And if you never love, you´ll spend half of the time regretting that you didn´t.