I keep wanting to weigh in on this topic, but I don't really have much to add that hasn't already been said! But you especially wanted female opinions, so I will speak anyway lol
I certainly wouldn't be put off in any way if I were playing a game that didn't tell me ahead of time that there were going to be lesbian relationships. I'd probably get really excited, especially if the story baits it might go that direction and then it actually does. (I hate in games and stories and such when a gay or lesbian relationship is hinted at and then never moves past that point. I mean, I get that it's likely because they want to dodge any negative impact, but BLAH!--- it makes me mad. :/ )
I don't entirely agree with the sentiment that it should be handled the same way as a hetero relationship would. That should depend on your society and what your society considers the 'norm.' If they so happen to be blessed to be in a space academy that doesn't have any sort of stigma towards same sex couples, then I think it is okay to treat it the same, otherwise it would be more realistic to show (even subtly, since you don't want it to be the central point of the game) what sort of impact it has on the characters themselves and those around them.
As for the question of whether it adds something or removes something game experience wise to me, it does neither. At the end of the day, it all depends on how it is handled within the story as a whole. If the relationship is believable and probable within the confines of the story, if it is realistic, natural, and given a proper level of growth - that is what will add something for me, and it will detract from the game only if it is clumsy, poorly written, rushed and forced. Oh, and I suppose it would detract if it was just put in for the 'Yuri is hot; fanservice' point, but I have a feeling that that's not a thing I need to worry about in this case.