Spoiler question

That, but also other reasons. It's more like, one reason after another accumulated in MC's mind.

First is on their first time actually doing it—Andante told him he's only dating him cause he's useful, right, at the end of S1 here. Hyoseop never forgot that shi (and honestly, NO ONE SHOULD EVER!!!!)

Second is because of Ano—the one that Onaip "left behind" on the SS Dungeon 10 yrs ago. HUGE SPOILER!!!!
Onaip used to be the no. 1 guild in the world, and Ano is their only guide. On the last SS Dungeon, they lost Ano to the final boss and had to escape without even managing to recover his body. That's the reason Onaip was formed, to get his dead body back. His code name, Piano = Ano. Onaip. Yea...
Anyways, ML hugged Ano's body and it's clear Ano was important to him. It was broadcasted to the whole world, and Hyoseop saw it. He thought Ano and ML was lovers. (NO. THEY ARE BROTHERS T-T Ano is ML's younger bro T-T)

Third is after Onaip went out after finally conquering the SS Dungeon, ML brought in another new guide to the guild—he wanted to use her for experimental purposes of the new device they got from the dungeon. Only guides can use it. Also, because he hated Hyoseop guiding other people, even his own guild members, so he wanted the new guide for them, so he can solo Hyoseop. Biggest mistake is ML never explained this to MC. So MC thought he's not needed anymore, and that ML will be fine cause he have new guide.

Lastly, MC believed that ML doesn't genuinely love him. He believes ML want him out of pure obsession, just an Esper obsessing over his guide. —This one stems from MC's past. He thought Andante was the same as his previous esper. （￣へ￣）

Wahhh can't wait for it to happen omfg

omg tysm ily

Thank you! So detailed. Can’t wait for the chasing and groveling arc, haha.