Yun Qi the backstabber boyfriend from her previous world followed her to this world. He was reborned into the body of a prince of another nation as gifted as Nangong Liuyun and looking as hot as he was from the previous world.
So the mysterious person who paid for the dragon ring to be found was actually Su Luo's real mom (who is not part of the Su Family in this new world. Su Luo is from another higher universe I keep calling the spirit world). Su Luo's mom told Yun Qi that she choose him as her husband and she must act as if he is betraying her so her spirit would go to this world. Her mom also told him to get to this world so Su Luo will meet him soon after being chased by a stalker apothecary who loves her new Apothecary teacher (getting him to be her teacher is coming up in another 100 chapters or so).
Yun Qi really does love Su Luo and knows everything about her but he is just as bad as Nangong Liuyun in showing it. He is the silent protective type...Nangong Liuyun is the deadly obsessive type...So Yun Qi tried to get her back but Nangong Liuyun keep getting in the way...Her mom had set up competition for choosing her future husband and Yun Qi competed with Nangong Liuyun.
On the night of Su Luo and Nangong Liuyun's marriage Yun Qi kidnapped her then tried to rap her. Eventually he gave up his life to save her and died...If Nangong Liuyun hadn't existed they would have gotten back together...
my hand is too tired from typing!!! Hope this answers some of your questions!