不贞的

例句：

1. 1. The couple's inconstancy has caused a lot of tension in their relationship.
   这对夫妇的不忠已经给他们的关系带来了很多紧张。
2. 2.He was accused of inconstancy by his wife.
   他被他的妻子指控不忠。
3. 3.Inconstancy is often the root cause of many problems in relationships.
   不忠往往是许多关系问题的根源。