Didn't think I would get a response to my earlier challenge, however it doesn't really address the main issues:
- Where will they be?
- What will be their new life roles?
- Do these futures for the girls reflect their aspirations?
Also from a game design perspective, post award ceremony there are 4 options, then you get access to 4 of 5 events and then the final event. Having a harem option means that you only get 1 of 5 events in the middle portion. This truncates the content for this option.
If there aren't any details. It becomes a 'And they lived happily every after' style ending. Don't think anyone is going to be happy with this scenario.
The only character that might accept an harem would be Tanya, if, and only if, she feels she's the only one you love and you are totally honest with her. But none of the other girls would be willing to accept a secondary role in that mix. Lia's people is quite conservative, her own maid seems scandalized when she sees Lia has slept with both Tanya and the MC. She's a queen who is expected to stay in her planet once she has experienced the space life, so if the MC wants to be her man, he should stay too, which goes against Tanya wishes. So even these two friends' goals are mutually exclusive.
Now, Kara only talks about having a quiet life with the MC and creating their own family. At no moment does she imply she would be willing to share that life with another girl, plus the same logic applies: which one would be willing to live in a secluded farm according to Kara's wishes? The intrepid pilot who wants to be the 'alpha female'? The most powerful queen in the Galaxy? I don't think so.
Then Tiffany. She's the most jealous girl, the one that keep insisting in getting the MC all for herself. Even Julia's training, which you see just as a 'porn-logic perversion route', is just a way to make sure she's the best and the only one the MC would ever need. It's not a route to make her willing to share, but quite the opposite: it's a route to become MC's only choice.
The fact that all of them are OK with the MC fooling around with others is only due to their confinament in the ship and their hopes to be the chosen one when this endeavour ends. Those pranks they tend to do against others when they feel neglected shows perfectly why an harem is never going to work with this roster. They are competing, not sharing. So it doesn't matter that you as a player, or even the MC as a character, could be willing to answer 'Yes, it is worthy'. Because the girls just won't accept that answer. They are free people, not your slaves.
I am not a creative person at all. All that I have written is only a very rough sketch. I tried to rationalize and objectively describe my very subjective vision of the game, the characters and the whole situation as a whole. And I think a harem ending is possible. This is only a possibility, of course, but it's not a small one. What follows is based only on endings that are joint with the MC, I will not touch on the rest, where the MC is not present.
Tanya is a very adventurous girl, she wants to surf the cosmos, travel to different parts of the universe. You don't have to be on every one of her flights.
Also, you do not need to fully immerse yourself in the life of Heleon. After all, Lia is the ruler, not you. Of course, you need to pay enough attention to both Lia herself and your future children, take part in some events, but not all of them either. It's difficult, but not impossible.
With Kara, too, everything is quite smooth. There is a house, a loved one is there, her people are safe. You also don't have to be there 24/7.
With Tiffany, of course, everything is very complicated. That way out of the situation can lead to both positive and negative results. But in this case, the main thing is to develop the right soil (I'm not sure if I wrote this correctly and whether it will be clear to you what it is for). And then...
Like I said, it's all just a possibility. It can end well, or it can end like in
The Witcher 3, when you tried to romance both Triss and Yennefer, i.e. with nothing or as in the
Dragon Age: Origin where you will be directly presented with a choice, i.e. we will return to those endings that are in the game. But everything is possible, the main thing is to do it all correctly and describe it.
Relationships between people can lead to completely unexpected places in fiction novels and other works. I remember how I accidentally read in the comments under YouTube about how ATTENTION FURTHER SPOILERS FOR MONOGATARI
You write that this is impossible, but I also remembered the Mass Effect ATTENTION FURTHER SPOILERS TO The Mass Effect
I cannot go into details. Because if you start to come up with a plot for this, you can get a whole new game. The MC wakes up one day and, as in Helltaker, says: "I want a harem." The ultimate goal is to create the most influential marriage union (do they speak English like that?), which includes some of the most influential women plus the MC (he is also a big shot). The only thing that comes to mind is that some unexpected event should happen. This event is like the Spanish Inquisition. Nobody expected this. The result of this will be that the girls realize that the MC is too important and irreplaceable in their lives and will come to a compromise with each other. Harem seeds should already be planted by now and this event will allow them to grow. Then the necessary actions and words on the part of the MC and voila, a very powerful family was created. In addition to harem fights, you can also add political intrigues, investigations, adventures, new discoveries.
The MC must also respect every girl. Everything must be done by mutual agreement. MC is not a character from the Miel games. He will have to find a balance between the members of the harem. Well, given their technology, he can travel from one planet to another, from one girl to another, to pay attention to each. He does not need to choose one place to live. Also, after repairing the ship, they can all gather on board.
I hope I was able to convey my idea and it did not disappear during the translation. I am an ordinary harem lover who did not get the ending he wanted and came up with my own, which I consider true. You gave the opportunity for this and I took advantage of it. In my answers, I relied primarily on feelings and sensations. How successful all this I can not say.