Not older and younger but definitely black cat x golden retriever:
The Dawn Split The Night
https://www.mangago.zone/read-manga/the_dawn_split_the_night_ilovecheetos/
The Pizza Delivery Man and The Gold Palace
https://www.mangago.zone/read-manga/the_pizza_delivery_man_and_the_gold_palace/
The Man Next door
https://www.mangago.zone/read-manga/the_man_next_door/
Boss Bitch Baby
https://www.mangago.zone/read-manga/boss_bitch_baby/
Gig of the Day
https://www.mangago.zone/read-manga/daily_part_time_job/
Did It Work
https://www.mangago.zone/read-manga/did_it_work/
No Moral
https://www.mangago.zone/read-manga/no_moral/
Don't Mix Business with Pleasure!
https://www.mangago.zone/read-manga/don_t_mix_business_with_pleasure/
Please Pay Attention To Me
https://www.mangago.zone/read-manga/please_pay_attention_to_me/
Sooo what I know is that Kang's Yeesu is one of them but... murderous/black cat older man x hyperactive/golden retriever younger man???