Jusei Shite yo Chizuru-san! -Hitozuma to Koi Suru Hitonatsu- by Lilith Soft - Adult Sex Game

Finally, it's summer vacation!
As high-school student Shiozaki Minato thinks about things to do during his time off he is reminded of his first crush, Chizuru.
Chizuru used to take care of him when he was little but had to move away due to her family.

That was ten years ago.

Minato quickly decides to visit her during his vacation when a woman's voice greets him from behind.
It is indeed Chizuru standing in front of him. She recently moved back to her hometown.

Minato is overjoyed to see her again, but his feelings are quickly crushed when he learns that Chizuru got married recently.