It's yotsuba and it's like that! What's all this bias, "she's a better girl", "she deserves better"...
If you think about it for a minute instead of just supporting one of the girls, that yotsuba being the bride is quite logical and the story ends well.
Otherwise there would have been an unhappy girl (yotsuba) all her life pretending not to disturb one of her sisters who got married,when she is the kyoto girl and they promised to support each other. And with that you wouldn't have any problem because your favorite was chosen? not very beautiful logic