Totally agree! Some also commented that Rei is too old for her and that Ren would be better suited but he also has an 100+ age gap so don't even argument with that. REI not only saw her as Erin from the get go (like you've mentioned) but he also is much closer to her personality wise (as he also acts childish even if he is so much older...he also wasn't considered an adult in dragon age for as long as Ren).
Ren really rubbed me the wrong way..I can't explain it but he was so...possessive in a low key creepy way, hell I even preferred the crown prince as a love interest over him.
We could also see how he actually loved Irene more as they were trapped in the trap, living out their secret desires in life. Rei dreamt if a future with Erin but Ren was with Irene and her returning his feelings so there is that proof.
U think a reason why Erin even got a crush on him was because of their close proximity since their stay in the demon world and because of Irenes memories confusing possible admiration Erin had with love.
I may read this wrong but I think the reason why Ren didn't stay with Irene in the end wasn't because he may have fallen in love with Erin instead but perhaps because of his duty and MAYBE to stay true to his clans tradition/value of dying with the oath. Even if the oath didn't manifest with Erin, the words had been said and a promise was given but he may have also realised he couldn't uphold it without risking the happiness of Erin, so he may have not solely cried due to the rejection of feelings....
Oops..the names confused me ..I mean Erin as in Rin and Irene as the goddess...sorry...
Idc what anyone say but this story is good and nobody can tell me otherwise. It has good balance of adventure, romance and everything else. The fact that rei is the end game and not ren makes it even better. Rei is one of the few people that actually love Irene as Irene and not Erin. So he deserved to be with her