He is not dating his first crush. Now he only has sex with a sexfriend. Since the time his first crush, shreddered his heart into pieces by shouting "disgusting!", there is always this "disgusting" in the back of his mind like a trauma. So he thinks feelings are prohibited. It's only okay if its the body so he doesn't mind even if it hurts.
But his sexfriend loves him and wants a real realationship with him. He shows him in public by telling him his love and not let go of his hand, there is nothing to fear, nothing is disgusting by showing feelings. He is reaching out a hand to free him from his fear.
I hadn't read this in a while so I revisited it to refresh my memory. It is obvious he is not dating his first crush after the country scene when we are fast forwarded to the present..My comment above is ONLY regarding pages 4-8 where I'm trying to get a sense of the depth of the initial trauma. I compare being rejected by your lover vs being rejected by your unrequited crush for a public display of affection. I think the former would be more likely to shatter an oversensitive heart.
I agree with your analysis of the story so far and I think the seme is #boyfriend goals.
Was he actually dating his first crush, the one that didn't want to hold his hand? It wasn't clear but I think that would be more traumatic than trying to hold hands with an unrequited crush...Anyway in traditional Japanese society public displays of affection was a no no, even for heterosexual relationships, but geez they were in the middle of nowhere...Also the Manga is marked as ongoing so there may be other chapters out there to translate..I hope