... does the character's question about her relativity with other characters give any advantage? In general: is this relationship system used for something ?.
If you look into the walkthrough you see there are different ups and downs in relationship with the other one (-1 to +2), dependent whom you ask about whom.
In fact, the relationship system is really fantastic, intelligently created and very deep. Its astonishing how much the devs put into this whole system.
Example: I look frequently if some action is going on in the park. Once I saw Ginny deep kiss Colin (at that time I did not know how miserable he is, v.062c). Later, I asked Ginny about Colin, and he discribed him like the worst man in the world. I asked Colin about Ginny, and he just answered "I hate her". So why this intense kiss ??
So I looked into "dirty cheater" (shift O), and both had a -50 in their relation to each other (max hate). Whats going on. The only possibility I could think of was that he blackmailed her (validated by devs).
So much "undercover". I do not look in the park (or forget to ask about Colin), you will not find out what's going on "backstage"
Another nice comment is from Ginny (about Hermione): "She took Harry away from me, I hate her!".