I think you are wrong.
My take:
Guest wants to be with Diana.
Guest cares about how Alba feels.
Guest is camera shy and won't have sex with anyone in that apartment.
Your assumptions make a lot of sense but one question we havent asked ourselves is why is the guest there in the first place since it doesnt seem to help their relationship:
1. she got invited to help them patch things back up
2. reason 1 but decided at the same time to flirt with Danna (which is bizarre coming from a friend)
3. she s jst crashing for a few days bt happen to come at a bad time (LOL)
or
4. she is there to help get rid of Alba
5. got invited by Danna for a threesome (camera shy so it wont happen)
The last two are LESS likely but hey ; who knows whats really going on...
my post might be pointless but am trying to understand the situation from different angles
:D
I think "none of the above".
I think Diana wanted to spend some time with her new lover at her own apartment. I think Alba was okay with the idea, but has found that she is, in fact, bothered by it.
On the other hand, maybe Alba is horny...doesn't want to have sex with the other two, either singly or as a threesome...but doesn't know how to handle her urges and the resulting emotions.
On the third hand (third? wtf??), maybe Alba, who Yuri says is planning to get her own apartment, is feeling sorry for herself because she's thinking about how alone she'll be...and also thinking about how Diana will have her new girlfriend to keep her company. That's kind of an added insult to her since she is, in effect, the victim here.
What the hell, let's go with a fourth hand, eh? Maybe I'm all wrong about the whole thing.