2. Change in looks
There is no harm in trying to look good. Of course, you want to look good and be presentable all the time whenever you go out. However, if there is an increasing amount of time your partner spends in front of the mirror trying to look good, then you know something is not right. On the other hand, your partner will always have this look of anxiety about himself or herself every time they come back home from somewhere. This is because they will worry about leaving any sort of marks or clues that would make you suspicious.