Ten Count
Complete | takarai rihito | 2013 released
2022-01-14 07:40 marked
Read this quite a while ago.
Papa Datte, Shitai
Ongoing | Serina Seo | 2000 released
2022-01-14 09:03 marked
Made into a short anime series you've seen.
Itooshiki Hibi
Complete | Sono.n | 2019 released
2022-04-18 01:59 marked
Couple met at 18 and 28yo, but are now in their 50s and 60s. Not sure what age(s) this manga covers, but this looks very promising. 5.5 chapters out so far, but still ongoing.
Yamada To Shounen