I read the summary and expected there to be a good reason as to why the MC denied his feelings however after reading it, right off the bat you already don't like the MC because turns out they were already dating for a while, when he just flat out lies and tells him it was all a lie and he never liked the ML. It crushed the ML and the MC saw that yet didn't bother to apologize or say anything.
7 years later when he returns to the island he keeps bugging the ML who is clearly hurt from what happened in high school between then as well as lonely after his grandfather died and left him to live alone. The ML begs him to leave him alone and the MC ignores him over and over, and then finally when the ML lets him in the light house it cuts to a certain scene where they are doing it but it seems like it was the MC who pushed him down and did it however we don't really find out if he did since they don't really talk about it other than the MC saying sorry for the other day so we are left to wonder did he or did her not get consent.
After like 3-4 chapters of the MC constantly bugging the ML he finally tells him the reason as to why he told him he never liked him in high school and doesn't even apologize. THe reason alone was absolutely stupid! He knew the ML wanted to stay behind in the island to take after the lighthouse that his grandfather wanted to pass down to him yet the MC wanted to leave to study in tokyo and for what? He didn't even use that degree for anything, he ended up returning back to work on a ship....like what??? What was the reason!!!??? He literally breaks the ML's heart by lying that he never liked him after making him fall in love in the first place (he initiated talking to him, bugging him to be friends and then made the first move) Poor ML was traumatized after that and doesn't even get a sorry.
We get a chapter towards the end of the manga where we see that from the ML's point and it just makes you not like the MC even more.
In the present when they start dating again it feels very stale, you can tell the ML is still traumatized and hurt, it doesn't even feel like a happy relationship you want to root for. This isn't cute or fluffy, I wouldn't recommend it.