Shirobako is one of the more realistic anime I’ve seen for depictions of real world adult life. Some things are still exaggerated, especially for comedic effect, but the work/stress/organizational dysfunction/interpersonal conflict bits hit decently well.

Easy: Journal with Witch

I’d say it portrays life in general realistically, and that includes adult life of course.

Wotakoi is my top choice, and comes packaged with a top-tier manga.

Tokyo Godfathers also portrays a realistic adult life, for a certain sort of adult anyways.

Barakamon

Just finish the season and read the rest of the manga

Not necessarily the shenanigans on screen, but the way each character interacts is pretty realistic I would say.

I’ve never wanted kids but wouldn’t mind if a little gremlin like Naru suddenly in my care.

Fune wo Amu seemed pretty realistic adult life to me