Rika revealed her past, and we learned about her strange and twisted view of love. She believes that by sleeping with other men on the secret account, she satisfies her desires and tests her love for Sousuke. In the end, she says she doesn't deserve to live because of all the harm she's done to the MC and decides to commit suicide, obviously trying to manipulate him since she's pregnant. My prediction is that Sousuke will forgive Rika and that after she spends some time in prison, they'll get back together, since she's expecting his child.