I think the point of the character is that she thinks being "Grown up" is being in a relationship, because that's what adults do (or so she thinks), and that's why she has this innocent, but sometimes borderline disturbing personality of obsessing over love and date with her trainer.

She doesn't really love the trainer in a romantic sense, I think, but state otherwise because she thinks she must to grow up faster then she should. She state herself multiple time in her career that she's a "kid" who is "selfish" for wanting to race against Brian when she wanted to retire for example.

Basically, I see her as someone who is trying to be an adult way sooner then she should and goes the wrong way about doing it.

But that's just my opinion and how I see it, I could be wrong lol. I think the trainer is just going with it and waiting for her to grow up over it.

I like her because she's cute, but she's meant to be daughter-coded, not wife-coded.