These tips come from by Dr. Robert Huizenga, The Infidelity Coach, of the Website: Break Free From the Affair:
Some of these signs of cheating are “tongue in cheek” while others are tell-tale signs that commonly appear with a cheating husband or cheating wife.
1) You find birth-control pills in her medicine cabinet, and you’ve had a vasectomy.
2) Mutual friends start acting strangely toward you. (They either know about the cheating or have been told stories about what a horrible wife or girlfriend you are.)
3) Your cheating husband or wife stops confiding in you and seeking advice from you.
4) Sets up a new e-mail account and doesn’t tell you about it.
5) He leaves the house in the morning smelling like Irish Spring and returns in the evening smelling like Safeguard.
6) She joins the gym and begins a rigorous workout program.
7) She buys a cell phone and doesn’t let you know.
8) He sets up a separate cell phone account that is billed to his office.
9) The cheating husband carries condoms, and you are on the pill.
10) Begins to delete all incoming phone calls from the caller ID.
11) Deletes all incoming e-mails when they used to accumulate.
12) He becomes “accusatory,” asking if you are being true to him, usually out of guilt.
13) Raises hypothetical questions such as, “Do you think it’s possible to love more than one person at a time?”
14) He buys himself new underwear.
15) He insists the child seat, toys, etc., are kept out of his car.
16) The cheating wife stops wearing her wedding ring.
17) Has a sudden desire to be helpful with the laundry.
18) Has unexplained scratches or bruises on his or her neck or back.
19) Suddenly wants to try new love techniques.
20) He/she fairly suddenly stops having sex with you.
21) He/she suddenly wants more sex, more often.
22) Supposedly works a lot of overtime, but it never shows up on the pay stub.
23) Picks fights in order to stomp out of the house.
24) You find out by accident he or she took vacation day or personal time off from work – but supposedly worked on those days.
25) Shows a sudden interest in a different type of music.
26) Spouse’s co-workers are uncomfortable in your presence.
27) Has a sudden preoccupation with his or her appearance.
28) Spends an excessive amount of time on the computer, especially after you have gone to bed.
29) He throws up a lot because he just ate at his mistress’s house and had to eat the dinner you prepared when he got home.
30) Your spouse is away from home, either nights or on trips, more than previously.
31) His/her clothes smell of an unfamiliar perfume or after-shave. You see lipstick on your husband’s shirt.
32) The amount of money being deposited into your checking account drops off.
33) You find items of intimate apparel or other small gift-type items that you did not give your spouse.
34) Your spouse seems less comfortable around you and is “touchy” and easily moved to anger.
35) You get calls where the caller hangs up when he or she hears your voice.
36) He/she loses attention in the activities in the home.
37) Your intuition (gut feeling) tells you that something is not right.
38) He/she has a definite change in attitude towards everyone in the home.
39) She uses a low voice or whisper on the phone or hangs up quickly.
40) She has a “glow” about her.
41) Atypical erratic behavior.
42) He sneaks out of the house.
43) She sleeps with her purse by the bed
44) She goes to the store for groceries and comes home 5 hours later.
45) He tells you can get hold of him at a different telephone number.
46) The telltale signs of a cheating spouse? Having to ask that question in the first place.