I learn this through experience: I used to think this way as well - higher you climb, harder you fall.

When you love, is it an unconscious willingness to give or is it because it is something we have to do, as a duty as a bf/gf?

There will be no disappointment if there is no desire.

You can love deeply, but when you fall completely - it goes back to this original objective - your willingness or your duty? If that's what you want to do in a relationship - you will expect nothing and your 'seemingly' fall is just an easy glide down the mountain. Sure, the sudden fall will frighten you, but you won't die from it.

P.S: What doesn't kills you, makes you stronger.