Yeah, but in Japan, which is where the story is set, friendship/obligatory chocolate is a thing. And it's becoming more common nowadays in there for girls give their guy friend a friendship chocolate. Usually friendship chocolate is less special than romantic chocolate, like it may just be one piece of shop-bought chocolate, or cookies while their romantic chocolate is homemade. I kinda assumed that a lot of people would know about this, I think there's a few example in anime? I don't watch a lot of anime myself, but one of the example I know is on Komi Can't Communicate. Komi gives a lot of friendship chocolate to her friends on valentine, both guys and girls. But yeah, it can get confusing when the girl does not say if the chocolate she's giving is friendship or romance, which is why I added in Risa's inner thoughts that it's an obligatory chocolate.
The reason Risa lies to her bf is about the chocolate is because her bf is the jealous type, that overreact to the smallest thing. MC already mention this to Natsumi, when when Risa hadn't choose yet, she hang out with MC but her bf call her cheating on him. If he was already jealous before they're even in a relationship, Risa know how much jealous and overreacting her bf would be if he find out she's giving chocolate to another guy, especially to someone who had a thing for her in the past.
Also Risa was the one who ultimately ghost MC, effectively ending their friendship, so she didn't reject MC to save the friendship. And she will learn that, while she's thinking of MC's best interest when she ghost him (to help MC move on), the way she did it is really wrong.
And regarding the dating term, maybe I just used the wrong word, but here's my understanding of the current dating culture, there's basically a few stages for a couple to be together.
Stage 1 -> Acquaintance
Stage 2 -> Friends
Stage 3 -> Getting to know each other better, or going on dates
Stage 4 -> Becoming Exclusive, or only seeing each other
Stage 5 -> Become gf and bf or get into a relationship through a confession or asking to be official, which is what MC was doing to Risa at her introduction
Though this is just the longer stages, some people skip stage 2, 3, or 4. I mean Natsumi skip step 3, and 4 when she jump MC. Stage 3 can also be confusing to some people, because if it's never specified, it can be interpreted as just hanging out as friends, or going on a date.
And when I say they went on a date, I meant they're on stage 3. And I think I specifically avoid the word "dating" and only use "they went on a date" (but I might have missed it). Because depending on each person or culture, dating could mean either stage 3, 4, or 5. So Risa and MC only go as far as stage 3. While I know that it can be sucks that people can go on a date with multiple people at once before they're becoming exclusive or getting into a relationship, that's the reality of today's dating culture. Especially for popular guys/girls, which Risa is in the story.
It was also mentioned that Risa had like 10 suitor before she narrowed it down to 2. This was because the other 8 decide to confess right away before even becoming friends, which she found strange.
She will have her redemption, which will be the one of the main focus on her chapter, but to sum it up, it won't be where she's always in love with MC and just realizing that after being treated horribly by her bf. I can't explain it all, but basically she's a flawed person, with some good points, and her chapter will talk about her flaws and overcoming that. But since she has not overcome those flaws in the current version, I expected that she would get a lot of hate. Which is also what MC was feeling at the start, though hate is a strong word, MC just resented her and overtime became indifference toward her.
But yes, if she's a virgin, she will be saving it for someone special, and thinks that her bf isn't one, which will make MC realize that she's having a relationship problem when she said that. (Like why would she stays with him if he's not someone special for her). As for why she's fantasizing about MC, it might actually be the opposite of what you think(?). She is confused about how she feels, yes, but rather than she's in denial about being in love with MC, it's actually she's starting to think that she has feeling for MC, while she's actually not. But like I said, not yet anyway.
Going into her storyline a little bit, which is a spoiler
Her storyline also won't be where she breaks up with her bf and gets into a relationship with MC right away. I don't think that's a healthy thing to do and will just make either MC a rebound, or a backup/second choice. And she's not breaking up because she's always in love with MC and regret not choosing MC (Though she will feel that way at first because it's all confusing for her), but rather because breaking up is the right thing to do for herself. So MC won't try to steal her or get her back, rather he and Natsumi will help her get out of an abusive relationship. Then MC, Risa, and also Natsumi will resume their friendship, and finally Risa start to falls in love with MC after she has fully moved on from her bf.
This is what I want to explore in her storyline.