Wait.. so did something ACTUALLY happened between them?? Im confused sorry ╥﹏╥

Well there's a flashback scene at some point where the rich family visits the orphanage Yeonwoo was held at (I theorise the mother was sponsoring the orphanage) and it shows they met around that time as kids. But based on what Rosa said in the latest chapter, they probably had more history than a meeting or two, yes.