Spoiler… kinda..?
The ML never had romantic feelings for his old guide. He only felt an attachment to him because of their pairing as an esper and guide. But due to a traumatizing incident between them, ML ends up overlapping the shadow of his old guide with MC solely out of fear and guilt. But his feelings for MC go beyond just their esper/guide relationship, they’re genuine and romantic in nature.
Hope this helps some.

I want to start reading this, but I hate the stories where the MC is at the shadow of a previous lover of the ML... Is this that kind of story? Spoil me pleas!