Something else I remembered, she actually moaned about no longer being the special "little sister like" of the house since Vi arrived.
Really? Vi lost the last member of her family and got no one and nowhere to live but you worry about your special house status? Sounds like a little kid to me.
Oddly enough, I'd use that very same conversation as an example of why she is (relatively) mature.
That conversation happens after the first movie night where Valentine and Viridiana both fall asleep. Valentine notices that Amrit looks like someone who wants to say something but isn't sure that they should. So he encourages her to talk and she opens up about how she's noticed how different he is with Viridiana around. She says "You're comfortable around her, you relax. The entire time I've known you, I think you've let me be that close to you maybe seven times. And only when you instigate. If I do, you move away."
Valentine denies it, but then immediately starts to second guess himself and wonders if she's right and he has been doing that. Then he asks her if she's jealous, and she admits it right away. There's no denial or anything. She says "So what? I know it's silly. And right now, Vi is in a bad place and you're helping her out. I'm just being silly. I got used to being the household little sister. And I feel rude and bitchy for even saying that with everything she has going on."
Everybody has moments where they feel jealous, insecure, scared, or whatever. What separates the mature from the immature is how you deal with them. An immature person who was jealous of someone else would do stuff like try to exclude them from the group, make passive-aggressive comments, and would never admit to actually being jealous. Amrit doesn't do any of that. She's been doing her best to make Viridiana welcome, and when she does start to get jealous at how Viridiana can get Valentine to open up and be at ease, all she does is have a private conversation with him where she admits to her problem and works through it.
That conversation ends with Valentine asking her to please talk to him if something is bothering her, because he wants nothing but the best for her. Which is what kickstarts the conversation about dating, and her making a move on Valentine. That's another thing some people see as immature, but I find that in the given context its not so black and white. Sure, dating your coach is almost always a bad idea, especially if your coach is a known womanizer, but in this very specific situation it might not be the worst thing in the world (depending on how you play Valentine).
Valentine has never done anything but make her life better and treat her with respect. The first time she took a chance on him was back when her friend encouraged her to go with him to train under him, and that paid off in a big way. Now she's got to know him fairly well, she wants more. She knows that this could go badly, but sees it as a chance worth taking rather than an immature fantasy about destiny and whatnot. Her first gamble on him was way bigger than this one, so is it really that crazy for her to take another chance on him?
If you do choose to keep things professional by letting her down easy, their conversation ends in a way that ever so slightly smooths out her unwillingness to take no for an answer.
Amrit: "You know, you've always been adamant that I should never give up on what I want."
Valentine: "..."
Valentine: "I have."
Amrit: "Just thought you should keep that in mind."
Amrit: "Good night coach."
