"Sorry I'm late. I was over at Joe's hou… I mean Janine's house. I was at Janine's house."
| January 30, 2017

It’s hard to believe (and accept) that our significant other might ever even think about being unfaithful. But it happens, and in many cases, the signs are right there in front of us — and we ignore them.

In the interest of protecting ourselves from heartbreak, we asked the experts to identify 16 key signs that could indicate when someone is thinking about committing the ultimate betrayal. Here's what they said:

#1. They’re guarding their phone.

Today, it’s normal for people to be attached to their phones. But if you get the sense your partner is hiding it from you, or they get nervous when you touch it or walk by while they're using it, that’s a red flag. "If this is a new behavior, be aware," says Jonathan Alpert, a psychotherapist and the author of "Be Fearless: Change Your Life in 28 Days." "They may also sleep with it by the bed, not keeping it lying out on the table."

READ: Does 'Sexting' Count as Cheating? Experts Weigh In

#2. Mood changes and increased irritation.

It feels as if your partner is more impatient with your quirks; all the things that they once found endearing about you, they now find intolerable.  This might be the result of your partner being conflicted — being with you but wanting to spend time with someone else. "Naturally, it will lead to frustration, moodiness and even anger. They may even start fights in an effort to sabotage your relationship," says Alpert.

#3. They have some sort of physical change.

It could be a change in perfume/cologne, maybe it's a new haircut. "The key is your partner goes through some sort of physical change and doesn't talk about it with you," says dating expert Yue Xu. "In a normal relationship, your partner gets his/her haircut and asks if you noticed.  When a partner is astray or thinking about it, they usually go through a change for their new partner."

#4. They stop planning for the future.

It’s been a while since they brought up going on another vacation together. "This is a big one," says relationship expert and matchmaker Samantha Daniels. "Remember how the two of you always talked about upcoming things? Vacations, events, purchases? Well, if he/she stops doing that cold turkey, and changes the subject every time you try to discuss anything related to the future, you should watch out and ask why this is the case."

READ: Is He Ready for Marriage? 4 Signs Your Man Is (or Isn't)

#5. They’re reconnecting with their single and divorced friends.

"Remember how he/she never wanted to hang out with their divorced friends because they were too negative? Well, if now, unexpectedly, your partner is choosing to hang out with those people, be on guard," says Daniels. Studies have also shown that divorce can be contagious, and the divorce of a friend or loved-one increases your chances of getting divorced, too.

#6. There is a change in sex drive.

This could be tricky to identify, because you might see a complete withdrawal from sex or you might see your partner initiating it more. "They might feel an extra charge of sexual energy and confidence as a result of this new flame and feel the need to discharge it with you. They may also be trying to compensate for their indiscretions," says Alpert.

#7. They’re emotionally distant.

It feels like they don’t want to communicate, or that you're on different pages. "When you´re watching TV, they’re on the computer. When you´re in bed, they’re watching TV.  This kind of emotional distance and absenteeism from the relationship is often a breeding ground for infidelity," says Sami Wunder, a dating and relationship coach. "It´s a clear signal that they’re emotionally disconnected and could be in search of greener pastures."

#8. There’s a history of cheating.

Past behavior is often an indicator of current or future behavior, even in relationships. If they’ve done it before, it only makes it easier to do it again. Alpert says family history can also be a predictor of cheating, as people learn to model their parents’ behaviors. "If there is such a history, have they talked about it? Processing it in a healthy way might help safeguard him from making similar mistakes," Alpert says.

READ: 3 Ways to Catch a Cheater, According to a Couples Therapist

#9. They add passwords to phones, computers and tablets.

If, randomly, your significant other changes or adds a password to their phone and/or other devices, you should be concerned, says Daniels. "They always shared everything with you before. Why is he/she changing that now?"

#10. Their idea of treating you is through gifts rather than time.

A cheating partner may substitute time with money when it comes to showing his or her affections. "You may see that you're getting more gifts, more trips, more surprises than normal, but simultaneously, your partner is spending less time with you. A cheating spouse has a tendency to buy off his or her guilt, but is not willing to spend more time," says Xu.

#11. There is a pattern that repeats.

For example, your partner is always out on a certain night of the week. "Their cheating has a set routine where he/she might sneak away on a Friday night, and this happens like clockwork," says relationship expert Audrey Hope.

#12. He/she suddenly has a lot of work.

Using work, or working late, is the oldest trick in the book. "If all of a sudden your mate is very busy, on a deadline, or has a work project that needs to be taken care of at the office during off-hours, be suspicious," says Hope.

READ: 3 Clear Signs You Want to Cheat With a Co-Worker

#13. Secretive about money.

This may be more typical with male cheaters. "When a new woman appears on the cards, and an affair is building up, money is bound to be spent as part of the process. In order to not warn or alert the current partner, the partner in question can become secretive about where chunks of money go. Credit card charges you cannot account for may also occur," says Wunder.

#14. He/she confuses information.

"Their points of reference are blurred, as time spent with you is confused with time spent with the other guy or girl," says Alpert. "For example, 'Didn’t we dine here?' is a clear indicator they’ve been there before and not with you."

#15. It’s obvious they’re lying to you.

He/she says they were at their friend’s place for dinner, but you know they weren’t because that "friend" was with you that night. "This kind of straight-to-your-face, remorseless lying is often an unmistakable sign that the partner has things to hide from you, and [he/she] is clearly not mindful of the damage their lying is doing to your relationship," says Wunder 

READ: 4 Easy Ways to Tell When Someone Is Lying

#16. He/she avoids eye contact.

As kids, we were told that looking someone in the eyes shows you’re telling the truth. If your partner does not, it’s because they’re feeling guilty. "They cannot stand to face you, so they will avoid looking into your eyes and hanging out with you face to face," says Hope.