Masha Timeline and Summary

Masha attends Irina's birthday party. She's not happy about this and is all set to leave, at least until Vershinin walks in the door.
Vershinin and Masha start having an affair. They both like the philosophy side of things.
Masha gets bad-tempered and mean when Vershinin has to leave to attend to his crazy, suicidal wife. What can you do?
There's a fire, and in the middle of the chaos Masha confesses her secret love to her sisters.
The army has to leave. That's a built-in break-up right there (they didn't have texting in Russia until at least a few years later).
As the army's about to march, Masha says fare-thee-well to Vershinin. She's heartbroken.
Kulygin accepts her without judgment. Or at least, "without reproach," which just as easily could mean that he's up on his high horse for showing-off purposes.
She joins the sister huddle and is by no means the cheeriest of the bunch.