Noun:

1. unfaithfulness by virtue of being unreliable or treacherous

2. the quality of being changeable and variable

falsenessn.虚伪；不正确；不忠实

ficklenessn.变化无常；浮躁

changefulness不确定性

faithlessnessn.无信不贞.

constancyn.坚定不移；恒久不变；忠诚；【生】恒有度

1. Constancy is therefore inconstancy held in check and confined to the same object.
   因此恒定不变就是将易变控制与局限在同一个对象上。
2. Constancy in love is perpetual inconstancy, inasmuch as the heart is drawn to one quality after another in the beloved, now preferring this, now that.
   爱所恒定不变的是它永恒的易变，因为心被心爱人一个接着一个的特质所吸引，一会儿更喜欢这个，一会儿又更喜欢那个。