Gekiama Kareshi wa Bucchouzura shite Yattekuru

Yura, a company employee, is living with his aloof boyfriend, Kaji, who works as a daycare teacher. Their days are so sweet and affectionate that even a single night apart for a business trip feels unbearable.
One day, a man named Namekawa is transferred to Yura's department — the same man who once made advances on Yura and was driven away by Kaji. Now holding a grudge, Namekawa tries to shake them by saying, “Same-sex relationships ruin your partner’s future.”
While Yura tells himself there's no need to pay it any mind, he can’t help but realize there’s a kind of happiness he can never give Kaji — especially since Kaji loves children...

(Source: Houbunsha, translated)

Note: Includes one extra.