I wish for them the same @irene
Here's Hitoritabi translation on Shinhye's Intagram post....
하나는 내가 맘에 드는거- 하나는 네가 맘에 드는거- 사이좋게 하나씩 :-)
understood it as one each of the photos. Like, there are two photos of them together, Jongsuk likes one of them more and Shinhye likes the other more, so she posted both in friendliness. Most likely they discussed which one to put (like how Shinhye always says she posted this photo of Jongsuk with his permission, etc) and in the end, this is the result.
Some people think it could also mean putting one each of ‘ppyong ppyung‘ and ‘bbiong bbiong’, since one is preferred by Jongsuk and the other by Shinhye.