higurashi

Please give it a chance and go read the novel. A lot of you complain that he's 18, but in the novel he's actually 20 (I’m guessing due to Korean age). Also, this ending reaches the conclusion of the main story, but it doesn’t include the extra episodes the author gave us afterward. Personally, I really liked it, it was a calm and enjoyable read, and of course, getting to know the characters’ thoughts better makes you feel more attached, so it hurts even more when it ends. The novel ends with the uke being 28 years old (Korean age). You can read it on Novelupdates

I found this on a forum:

So llic and Sayan been together for 20yrs (10yrs then timeskip to another 10yrs)
Ilic doesn't seem to see it as a full romance, he never said I love you to sayan but he knows after so many years that Sayan is his partner.
Now llic has a dream and in the end of the dream Sayan dies, he wakes up.

So at the end of the story he's with Sayan (alive) beside him but he's thinking that all the things in the dream are happening in reality. So to put it this way, its foreshadowing that Sayan is to die sometimes shortly after the ending of the novel. It's also bittersweet because Sayan loves IIic but llic never really seem to be in love but the same he was (its kinda hard put, you would need read the novel to understand). [EDIT: oh I found the perfect phrase for this, it's that llic will never love Sayan the way Sayan wants him to love him despite them being together for so long]
Some say he did die at the end but either way Sayan does dies despite him being alive at the end. It's also mention how he's sick but do keep in mind, at this time they are old