After doing a bit of digging, I remember a similar NTR title, "Charao ni Netorare". The MC was also someone looking to break into the film industry and also lost his gf, Charao, through the machinations (though calling it that gives him too much credit) of a playboy. It ends with the playboy showing off his exploits with Charao, causing the MC to crash out as he walked away.
Skip forward a few years, MC becomes a prolific director and is happily married. He mentioned how he was cheated on in his youth, but can't even remember the girl's name or face.
The playboy ends up in some sort of scandal involving his promiscuity and his looks have clearly left him far behind.
One of the few NTR stories that have actual consequences for the perpetrators and with the MC the one coming out "smelling like a rose" in the end.
If GraPara ends in a similar way, I think I'd be OK with that, but, again given the author's history...yeah...😓