1. He/she loses interest in sex
Lost of interest may be a huge warning that they're getting it from someone else.
2. He/she is on their phone a lot
Not only checking it more than usual, but being secretive about it as well or trying to hide what they are doing while standing/sitting next to you. Changing his/her password to open phone.
3. He/she makes changes to their appearance
They've already impressed you enough, you're theirs. Yeah they may be wanting to switch up their look up or may be trying to impress someone else.
4. He/she suddenly needs to work all the time
This is the most obvious & the biggest "go to" trick. They usually go out of their way to make time and now suddenly have none at all.
5. He makes massive cash withdrawals
It's the only way to cover his tracks. No paper trail. Well unless he forgets to toss the receipt.
6. She starts distancing herself
Emotionally detaching is what a lot of women (and some men) do to prepare themselves for the final outcome. Want to go out with "her friends" not "our friends" or needing time to "find herself"
7. Your gut tells you something is wrong
Intuition is much more powerful than you may realize. Don't ignore it.
8. New interests
Suddenly being intrigued by a new diet and exercise or purchasing new perfume/cologne and clothes