When you first start to date someone and they seem normal but as time goes on their craziness comes out. 

当你最开始和某人约会时，他/她们看上去很正常，但随着时间的推移，他们疯狂的一面开始显露出来。

Adam: I thought Susan was a cool person until I moved in with her and turns out she's a major closet psycho.

亚当：我开始以为苏珊这个人很酷，但接触得多了，才发现她真是个不易察觉的神经质。