Bruh, come on Risako you don't thought Kaoru were gonna give up on Reiichi that easily ? She was rejected time and time again, don't think Reiichi going out with someone who seem to barely love him will be enough to make her give up and come on did you really think she would have not put distance between you ? You kinda steal her crush for no apparent reason and you act more friendly as before. Of course she ain't gonna accept it like that. Risako is not very good at understanding Kaoru or at least she don't understand how much Kaoru love Reiichi.
That's said here, who Risako is jealous of ? The flow of the conversation imply she was jealous of Kaoru but i'm pretty sure she was jealous of Reiichi to have past so much time with Kaoru. Hell i think what Kaoru said during all the page is about Kaoru and not Reiichi, she don't understand her feelings for Kaoru. To no one surprise, Risako is gay for Kaoru but she know she had no chance because of Reiichi so she try to make Kaoru give up but she underestimate Kaoru's love and end up hurting herself.
And i still think Risako is trying to make Kaoru give up on present time, hence why she asking for the baby to Kaoru. She know that Reiichi don't want one and that would make them fight. She is also probably using the accident and the unfortunate encounter to her advantage. That's said, even if Kaoru decide to really give up on Reiichi, I don't know if Kaoru will go to Risako, especially when Kaoru think it's partially her faultif that's happen and well there is the Uta's factor but as for now, Uta is out of the loop.