Yep you are absolutely correct!
Their marriage is a sham. Doomed from the start
Osiris made seth n nephyths marry :'). Seth's soul is unstable fragile n on tenterhooks of breakdown. Not only seth suffered a botched ascession like anubis but Osiris kept forcing him to break taboo (remember past, gods arent allowed to) n due to this as penalty he kept breaking and osiris kept mending him to prevent him from extermination but guess how he mend his cracked soul each time? Nephyths
Nephyths is goddess of peace n harmony n has powers to bring peace to anyone. Each time osiris broke seths soul, neph healed him n pieced him together. So obv they got close but So u could see neph was the sedation or life support plug osiris kept to leash seth and also he purposely made them marry to keep seth in control and also keep him very close by his side. They did have a good happy marriage BUT neph loved seth as her husband god of war n sand but did she love him for truly as himself? But they had a misunderstanding filled rushed end which one day or the other had to happen to resolve n part properly.
Seth loves horus. He loves him deeply. He's the only one seth had fallen for by his own choice. Last two recent chp there are so many panels showing us that. Seth is a tsundere but he is a veryyy emotional character u can see in the panel where mirror says horus love is fake, seths eyes go vacant as if he's in a blank shock as he mumbles the word fake. Also his insecurities are crippling cuz of osiris and when mirror said horus doesnt love him but was charmed by mirror's magic seth fell for the lies. He's heartbroken inside Last chapter panel was "i knew nobody could love someone like me". Mind u he wasnt planning to break up yho. He kept saying we'll talk abt this later but horus thought he would throw him away n go back to nephyths. Poor shylaasss.
I just dont think they could go back to being together after everything that has happened, not only that he did get into a relationship with horus so leaving him for his ex sounds like he hasnt matured but anyways, we proceed. Maybe he just needs the closure but im not sure, seth looked excited but not happy as he is with horus? If that makes sense.
Hope hathor dies