In all my routes I break the relationship with Miru before the trip (I do not like the character, I find her annoying and not so attractive compared to Leia, Katie or Dana).
Most people agree with you and that's one of the reasons why Ocean is doing the rework. Miru route feels so weak compared to others both because of her model and her shallow story with MC.
Now we saw her new model already and it is like much better so thats a huge plus. Also her story is getting revamped, Ocean talked about focusing Miru more at the start and her having more screen time. I already redeemed Miru in my eyes when MC goes into shock and explains the importance of Miru and how they met at the past. That sequence alone in 0.6 was more than what Miru got in the past. So I have no doubt reworked story will be much better for Miru.
If you answer no to Dana's question I dont understand why you have an -RP with her if the MC is no longer with Miru
If you broke up with Miru already you cannot say no since Dana and MC talk about it first. If you are still with Miru, MC talks about how being alone and lonely isn't the same. Then Dana asks if Miru does it? Meaning does she help with MC's loneliness.(Indirectly like asking if he truly loves her)
If you say no this is her answer;
She is clearly disappointed and you lose a RP. It makes sense because Dana's character is all about commitment and sincerity. She will not respect you if you are still together with a girl when you feel lonely with her. It says a lot about her character when you get +RP point with her if you confess being with another girl helps with your loneliness. Dana gets a point because of MC's honesty and commitment to her partner. Sums up her character quite nicely.
Dana is unique
That she is.. Honestly every girl is unique and that makes why we love Ocean's works so much. At least that's one of the main reasons for me.
Since you seem like a fresh account, I suggest you to check out his other game
Summer's Gone. Its within the same caliber as WIAB.