There is a rematch button

@General-Advance
It is hard to explain Sportsmanship with a few words. Such values need to be passed on at young age(Coach, parents etc), so to understand them in depth.

(Sportsmanship)None owes you a handshake after an official game, none will beg for it.
(Fair)There is a difference playing with Black and White pieces, so having a pair of games is fairer for both.

Being aggressive on this issue(like @Sarg0n ), requires an understanding of those values and thus the choice to attack them instead of follow or ignore them

None owes a rematch to anyone but it's the right thing to do, if you are able to... That's all.

PS. The flashing rematch button needs to be stopped when the opponent leaves.

Sportmanship can only be given/donated and not enforced/demanded.

Bothering opponents with home-invented „rules“ is not sportsmanlike. Use the button or don‘t use it. But don‘t talk about it or open useless threads.

I had an opponent who kept hitting the Rematch button, losing games, and then this happened and he was temporarily playbanned:

I think we'll have to agree to disagree. I sometimes give rematches sometimes I don't. Sometimes I'll ask for a rematch and other times not. Attaching 'right thing to do' to your statement like it's some moral issue seems ridiculous to me personally. @ZeldCrown

@ZeldCrown

After you play a game with the black pieces, your next game will almost definitely be with the white pieces, regardless of whom it is against. Are you experiencing some kind of bug that prevents you from getting one color as much as the other?

What difference does it make to you what the name of the completely anonymous player you are playing on lichess is? Everyone has the same number of whites and blacks against the same distribution of relative strengths over time. This is not a serious issue, just another way to justify taking losses personally and trying to "get revenge."