After replaying the game for the third time since you updated, I think I understand why everyone is so drawn to Telio. We have met one RO thus far, and our interactions with Arthur can be quite complicated. We have to be deceptive with him, at least to some degree, whereas immediately after meeting Telio he is protective of us and accepts us as a half-elf. It also actually makes a lot of sense for the MC to get heart eyes over the second child they've ever met, who helps and supports them. Especially because MC has really had friends before, and they are likely going to seek the feeling of safety Telio provides, since it appears their family is becoming increasingly separated.
Psychoanalyzing aside, all that is probably why a lot of us players fell in love with Telio. It is a testament to your writing actually, that we are so connected to our MC and are naturally leaning into and feeling our character's potential emotions.