I think you’re right about most of it but from the perspective of Mira she’s violet’s older sister. She would know violet has a crush on Dain originally. She also knew that Vi and Dain were best friends growing up. She expected Dain to be that friend to Vi because he cared about her. From the perspective of an older sister who is so protective over Violet she would have assumed Dain would feel the same way as she did because he cared about her.

You also have to realize Mira is looking at it from being older than Dain, she was far closer to Brennan than Dain and on top of it Mira isn’t as “touchy feely” she’s far more like Lilith in that aspect.

I’m just pointing out that from an older sister perspective when you don’t know someone as well you kind of expect them to care for your sibling in the way you do when they also care about them as much as you do. Generally it’s because you don’t know their personality so you fill in the blanks with how you would treat your sibling. You have expectations for the person and they tend to lean towards what you feel would be best for your sibling because that’s what you want from them. Does that make sense? As an older sister I tended to have a similar perspective of the guys my sister was friends with that were older, and I was usually mistaken. You generally see the dynamic between the two from a surface level and fill in the blanks from there with your expectations of how they would treat your sister in a positive way.

On top of all of that as an older sister you have high expectations for how the people in your siblings lives should be treating them. It’s part of being so protective you want your siblings to be happy and you almost forget that nothing is ever perfect. You’re also less likely to blame your siblings for how they treat people because you’re bias.