https://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_668378/

Summary:
His girlfriend's cuteness is far out of his league, but she's an influencer whose popularity is on the rise.

Since her popularity began to rise, she's obviously gotten too cocky, and he's always being made to help with photo shoots, with her treating him like a complete chore.

She also seems to be cheating on him, and won't let him have sex with her.

His feelings for her have cooled, and his sexual desire is overwhelmed, so he turns his attention to her older sister.

Worried about her sister dating influencers with seemingly shady personalities, the older sister ends up having an affair with the protagonist, on the condition that he stays together with her sister.

Wishing that her younger sister would date a kind, earnest boy like the protagonist, the older sister is very caring towards her younger sister, but she becomes increasingly addicted to sex with the protagonist.

One day, the younger sister witnesses the two of them cheating...