Yahari Ore no Seishun Love Comedy wa Machigatteiru. OVA

やはり俺の青春ラブコメはまちがっている。OVA「こちらとしても彼ら彼女らの行く末に幸多からんことを願わざるを得ない。」

One morning, Hachiman Hikigaya contemplates the superfluous nature of marriage and its misleading image of happiness. However, he is forced into confronting his skepticism when the Volunteer Service Club is tasked with assisting a local municipal magazine advertise the allure of marriage to younger people. Unfortunately, neither the club's advisor, Shizuka Hiratsuka, nor the other club members have any firsthand experience with the subject. With only one week until the deadline, the group must quickly learn about the intricacies behind the special ceremony, even if they have to resort to more creative means!

(Source: MAL Rewrite)