Yeah I do agree with you...
I love to see when people have great understanding of all characters. The author wrote them in a way that I can see where each of them is coming from, and how every single one of them believe they’re in the right (which is pretty realistic). Hestia is a great character but she’s also doing a lot for someone who didn’t ask for it. I also understand how she sees (at least at the beginning) them as characters NOT real people, and if she could return to her og world she would. Just like you said Caelus is her only purpose, so obviously she latched on the only person who keeps her going (which by itself isn’t very healthy).
I've seen a lot of comments telling that Cael "doesn't deserve Hestia considering all she has done for him" and wanted to talk more about Hestia and her reasons for doing all that. So first, I love Hestia, she is a great character, and yes she did a lot for Cael, it's thanks to her that he didn't kill himself, she deserves credit for all she did
BUT I also like Cael and I think that he has every right to still have conflicted feelings for Diana and the crown prince, and even if his actions are not what Hestia would do if she were him he should NOT be mad or seek revenge at his ex-friends if he does not want to. At the end HE is the one who has been hurt, not Hestia, and if he just wants to move on with Hestia and not resenting anyone, he should be allowed to.
The thing is Hestia's whole life revolves around Cael, it's cute but in truth quite unhealthy.
She wants to do so much for him that she weirdly doesn't really care about what HE wants sometimes. It's like she knows better. I find it especially obvious with Diana. I hate Diana too, and I love the way she is being dealt with currently but the fact that Hestia says "it's for Cael" doesn't sit right with me. Revenge is NOT what Cael wants, it's what Hestia wants. Hestia is so involved in the cause of "saving Cael", but she is not Cael.
The fact that her revenge is so personal show to me the flaws of her character. She is both selfless and selfish. She adores Cael and wants to do everything for him but at the same time she is obsessed with him because without him she would be alone without any purpose. What she does for him is really great and deserves to be praised, but it's also something she does for herself, because without all this revenge she would not know what to do. The sad thing about her is that she was left alone in an unknown world and she had to grab into Cael and make him a sort of god in order not to become crazy and lose herself
I really hope that she will be able to open herself more to Cael in future chapters. Being so obsessed with "doing everything for him" is envoyable but can't last forever. It makes her unable to evolve as a character and it prevents her relationship with Cael to develop into something romantic since she only sees herself as an instrument whose only purpose is to avenge him and make him better, and nothing else
Just my opinion