Exactly!! He just want to move on and not just with his life he wants Hestia to be happy with him. He wants her to not be so hung up with revenge anymore and that's completely valid because revenge isn't the perfect solution but just moving on with your lives is. Even though Hestias obsession with getting revenge is valid she needs to learn to live her own life for herself not just taking revenge for her bias
The worst part is Hestia hears this - the man of her dreams saying he just wants to be happy with her instead of focusing on shitty people - and thinks it means that Kael has gone back to square 1 and now cares about Diana she's so up in her own head with this obsession that anything other than that feels like betrayal to her, even the most well-intentioned stuff
Honestly I can't blame Kael; everyone is talking about how Hes has done so much for her revenge in Kael's name, but Kael just wants to move on with his life, and that's completely valid! Hes is so focused on getting revenge that just from hearing Kael say Diana didn't need to apologize anymore, she got pissed-- but isn't it Kael's call if he accepts the apology or not?? He was the one wronged, so whether he truly accepts the apology or just says that to shut Diana up, it's his choice and his choice alone. You CAN'T be the judge in his stead.
Hestia is way too obsessed with this; she shouldn't let her whole life revolve around 2 shitty people. Just bc she spent so long planning this whole scheme doesn't mean Kael should sit there and let her have at it when it's obviously becoming unhealthy. He doesn’t even need the revenge she says is for him!! He has said that multiple times atp!! Girl go on a honeymoon with your man and try to find joy in other places in life ur brain needs a vacation