It's easy to misinterpret any of the aforementioned signals as infidelity when in actuality, there is a perfectly reasonable explanation. But, if you start noticing that the signs are slowly piling up, and she's recently admitted she's no longer happy in the relationship, you might be on the verge of a full-fledged confession.

Guilt is a tricky emotion, and she might feel that by fessing up to her flailing satisfaction in the relationship, she is offering you (and herself) an explanation for her selfish actions. Or, she could be gearing up to act on a long-held impulse, and making her excuses in advances so she can later utter, "I told you so," with aplomb.