Lol. :) Best post ever:))

Trully agreed. There is no stable explanation for it, so its left to your imagination. The only and most appropiate explanation is one of yours, Adokat:
The witcher, the best monsterhunter in the galaxy, the fear of nonhumanoids (even trolls beg him) a fearsome killer, is more human and sensual than any charachter of the game by observing that ladybug and letting it fly.
It makes the impression that he knows truly how nature works. Which life can be spared and which one should be eliminated. By this act proves somehow his knowledge and right to have Yennefer, the fabled perfect women.Proves that he is not a monster, a mutant. He has more soul than any other.

It's actually explained in one of the books geralt has. Can't remember the specifics but I know is related to Geralt's and Triss Ending. Either there or on the Journal. Would have to check this is out of the top my head.
Correction: it's about Geralt and Whoever he ends up with.

An explanation that insists on stopping at the ladybug being a thing of nature and beauty, a pure and fragile thing that Geralt simply chooses to let live, and insists on declaring that there is no deeper meaning, is not much of an explanation at all but rather an attempt to foreclose discussion.

Had it been anything other than a ladybug, there probably wouldn't be this discussion. Had Geralt done something other than watch with great concentration as it flew away, there probably wouldn't be this discussion.

But it was a ladybug, and Geralt did watch closely as it flew away. Not only that, it is the central event of the scene. For that moment, there is no Triss, there is no gate, there is only Geralt and the ladybug. So it's either something non-trivial, or it's a cutesy, sloppy waste of the key moment of the ending. I'm giving the authors the presumption that it's the former.

Among the many superstitions held about this much-loved insect is the one that if you let a ladybug fly off from your hand, the way it flies will be the way in which you will find your true love. In a game and a world that is intentionally packed with European folklore, the idea that this carefully placed and composed scene means anything less is a non-starter.

At the end of the game, Geralt knows who his true love is. On the strength of this scene, he now knows the way he must go to find her.

I had a bug fly into my ear once, and for over a day I could feel and hear it buzzing around in my ear cavity (and don't bother, I've heard all the jokes).

I had to go to the local doctor and get the little bastard flushed out.