The last scene after the credits is not a dream, it is in fact the future. Where we see our old MC as an old, grown man. The dream I was talking about is the scene where we see MC's 'future daughters'.Wtf this guy really thinks MC will fuck his daughter because he named it serena LOL. He named it that way to thank and remember the help of an important person who sacrificed herself to help him has this great happiness. After thinking back, I think this ending was really good. That shot for the MC was like a "wake up call" for him. He is carrying a huge responsibility towards the people he loves and loves him but he is too careless, subjective and cocky.
The last scene I thought was a small scene in the future, not a dream. So that dream created by serena proves that she's still there just can't interact with the mc anymore? If so, the ending is quite good because the drama makes the story more emotional, helps the mc grow up and helps himself and others realize each other's responsibility and importance.
Good luck to your next game. I understand people's anger towards this ending because they expect a peaceful and perfect ending especially with harem games. Plot details to make the story more exciting, more emotional, help understand the characters more deeply and help them develop themselves are necessary for good vn but in my opinion they should be happens at the beginning, middle, or any point in the story other than the ending. If you say that sometimes life is unfair and not what everyone wants and that applies to the MC, but this is a harem game, it is already something of a fantasy. People choose pure harem games like this because they expect it to be filled with happiness at the end
If you want Serena to sacrifice to make it more meaningful, you should put it before the ending. Maybe many people still don't like it but it reduces people's anger because it will calm people down after serena's disappearance, they focus on looking at happy scenes and lewd scenes XD and also understand The message you want to convey through Serena's sacrifice. You go from happiness-> drama-> pain and sadness--> happiness again but the last "happiness" has too few scenes to comfort everyone after the previous drama scene
I'm going to extend the ending a little bit more to give more context of MC's situation, tho.