Okay, the biggest spoiler is that not only does Su Ruan has a system, but she is actually reborn, and not just reborn once but 5 times. In her original life, Su Ruan found the system that was originally attached to her grandma. By using the system, she went from a lower class girl to dating lots of upper class men and living a life much more luxurious than she has ever before. It was here where she met Lu Xingyu and fell for him because she saw how gently he treated MC. She attempts to kill MC and take her place but she ended up in a dead end and dies. Then, in order to be reborn, she gave up her twin sister's lifespan to the system who uses the energy gained to give her another chance to start over. Once again, she tries to capture Lu Xingyu and succeeds but she ends up killing the MC and causes Lu Xingyu to go crazy. This leads to the ML showing up and throwing Su Ruan in a mental hospital (or jail I forgot), and forcing Lu Xingyu to go overseas. This is also when Su Ruan meets Xie Jinxing for the first time and falls for him because he was better than Lu Xingyu in every way. She developed an intense obsession to become his wife so she uses her father's lifespan to restart. This time, it plays out about the same as the novel MC read. The bodyguard who threw MC into the ocean was charmed by Su Ruan's system. But once MC dies, the ML goes crazy and once again, sends Su Ruan to a dead end. Su Ruan then attempts to use her grandma's lifespan but her grandma, knowing what she did, cursed Su Ruan. So when she restarted her life, she becomes so unlucky that she died not long after. Using her grandpa's life, Su Ruan also didn't live long enough because her grandpa was meant to die soon anyways. Then the only living family member left for her to use was her mother's. This time, the system said it won't kill her mother right away, but will make her mother weak and as long as her mother lives, Su Ruan will live. I think it was also in this life that she gains an unexpected skill. She is now able to make anyone fall in love with her and unable to deny her requests. So she attempts to use this skill on the ML and he becomes unable to resist. However, this does not work in the presence of MC. So whatever ability she had, whenever the MC appears, the ability just disappears.

Then it is revealed that in every life, the ML has always loved MC. Every time he has fallen for her when he first saw her. This is why Su Ruan's system couldn't charm him until the 5th life. Also in each life, MC and Lu Xingyu were always meant to break up. Even though in the first life they loved each other at first, eventually they were not meant to be together in the end. Lu Xingyu also starts to remember some of the past lives where he and MC were in love and he also learns that Su Ruan must have something to help her make people listen to her. So he turns against Su Ruan and tries to get MC's heart back. But at this time, MC no longer has feelings for him. It's a bit heartbreaking when the author reveals that Lu Xingyu went crazy every time MC dies and that every time ML was drugged, he always choose MC only to have her die in the end, whether it was being ripped from his arms or when she was trying to hid in the room.