And then. . . .
Then you can really throw a monkey wrench in by having parts of your story need to take place in certain seasons. Or get one of the women pregnant. A single event is just fine. If one thing has to take place in the summer, everything else can be fit around them. It's when you know that this takes place in the spring, that in the summer, and the other thing in the winter -- or know she gets pregnant at this point in the story and gives birth then -- that you have to fit that sequence in, too.
True, if you contrive the right worldbuilding, you can do what you want with the seasons and pregnancies, but that doesn't fit all stories, and if you make it too obvious that you set it up for convenience it weakens the story.