I havent read it but what I got from the SPOILERS on reddit:
No, the MLs dad is a pedophile who had been molesting & grooming the mc from a young age (before his first heat).
The day Winston saw them in bed it was a similar scenario but the mc was spiked/drugged with heat inducers. The grandfather intended to drug & rape the mc but started to feel guilty(?) bc the mc kept asking for Winston even in the drugged state so no penetration occured.

I debating reading this but did the uke actually have an affair either the seme father??