Except River and Forrest also care about each other...he can sense her feelings, soooo?
Soooo... I forgot about that XD
I don't know how this works anymore
Heil cannot hear the thoughts of anyone he truly cares for--whether romantically (for River) or friendship (Lily + other Clandors except for Ilya who is his goblin servant). I say care for not love using the exact phrase in this translation.
http://www.mangago.zone/read-manga/the_god_of_pain_s_groom/uu/iur_chapter-36/pg-8/
Heil has 3 powers unique to him..
Telepathy..mental communication between him and whomever, even River right now. He is using this power in Chapter 27
Mind reading....infiltrating someone's mind against their will or without their knowledge and pulling out memories, thoughts etc. (this power is affected by his feelings for the other person)
Time manipulation
So far all we know is River is empathic but he cannot read Heil's emotions, he can read Khoal's emotions and his sister 's as well as human strangers. We want to know why he can't feel Heil's emotions so we can rally behind that heil x river ship with confidence.
River can't feel Heil emotions and Heil can't read River's mind because they care with each other (this happens involuntarily)
River CAN feel Khoal emotions, sooooo... ¬u¬