A summary I found online.
Spoiler ahead:
>! Summary (from GoTwoPlays) - Yoshida takes a 3-day leave to go with Sayu to Hokkaido - Issa prepares a ticket for all three of them - Yoshida and Sayu go sightseeing - Sayu finally faces her mom in front of Issa and Yoshida; Mom belittles Yoshida in front of Sayu, saying Yoshida has no reason to interfere with Ogiwara affairs, which includes Sayu herself - Sayu defends Yoshida and his goodwill, and Mom finally shows her true colors by blaming Sayu for everything bad that has happened to her and tells her "I shouldn't have given birth to you." - Yoshida and Sayu spend time together, going to her school, and sleeping together for the last time - Yoshida goes back to Tokyo, alone, feeling emptiness both in himself and his apartment after Sayu left - Yoshida is surprised to see Sayu again because she has a copy of his apartment key - Sayu straightforwardly confesses that she loves Yoshida. - Yoshida says she's bluffing, but she shoots back and says she's serious. - Sayu asks Yoshida if she has a chance to be his lover if she didn't have a key to his apartment; Yoshida low-key evades the question by telling her that "If you didn't have it, it's probably impossible" - Yoshida tells Sayu to go live her life and don't worry about him, but Sayu tells Yoshida that she intends to do that, but also promises him that she'll come back to him when the time is right - Yoshida struggles with his reason, telling himself that "No." would be the right answer. - However, he instead told Sayu: "I will not wait for you, but if there is even a very slim off-chance that we'll meet again, I'm looking forward to it" - They both bid each other farewell, officially ending their cohabitation - 2 years later, Yoshida, now 28, is still working in his company along with the other girls (Ao, Gotou, Mishima), however there are no implied relationships with any of them and they are all in good terms - Gotou invites Yoshida to dinner, something she's been doing for 2 years; it is implied that Gotou didn't go through with her confession, but eggs Yoshida for a relationship, which Yoshida shrugs off - Yoshida recieves a call from Asami for a meetup with Sayu and leaves Gotou; this cements the fact that Yoshida still puts Sayu as first priority above everything and that he secretly or unconsciously upholds his promise to meet Sayu even after 2 years - Yoshida arrives at the lamppost where he first met Sayu and finds her there, they exchange pleasantries - Sayu says "I'm home" to Yoshida, basically implying a start of a relationship and continued cohabitation/live-in life!<