Please tell me what manga is this

I think the last chapter was the fl waited for her ml at a tower, they promised to watch the snow fall together at midnight during her birthday but he had forgotten about it since he was busy and she was locked while she was still on top of the tower. Ml went to look for her and remembered their promise, that's when he found her at the top of the tower, then they kissed? I don't remember but help, I read it while I was sleepy, I couldn't remember the title and forgot to save it. (Royalty AU)