Even those of us in the happiest relationships have reason to fear cheating if our partner’s behavior seems off. But when should those changes signal alarm? Fox News talked to celebrity relationship expert Audrey Hope and author Jenna James to learn the top signs of cheating so you know when there may be cause for concern.

If your partner is exhibiting any of the behaviors below, Hope and James advised to talk it out — but to avoid an accusatory tone.

Here are some possible signs she’s cheating — or not:

1. Her schedule follows a new, repetitive pattern
If she consistently disappears on a certain night of each week, her “commitment” may be a sign of cheating, Hope said. However, that night may also be when she’s hitting a new workout class, or taking time for herself by getting a manicure or having a weekly night out with the girls. Don’t jump to conclusions until you know for sure if that’s the case.

2. She suddenly has a lot of work/takes business trips
“If all of a sudden your mate is very busy and has a work project that needs to be taken care of at the office during off hours, be suspicious,” Hope said. Yet, your sweetheart may have been assigned a new project or perhaps a new boss who is making heavier demands. Ask her if that’s the case, and if not, there may be reason to believe she’s with someone else.

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3. She goes out with her single or divorced friends more
Misery loves company! “If she suddenly spends a lot more time hanging out with what she says are her girlfriends, and is gone long periods of time with late nights out, this indicates she is at least dissatisfied with some aspect of her home life,” Jenna James, author of “Bait Him Back and Bait Her Back,” told Fox News. But the new outings also may be a sign of a busy social time for her with post-work parties, weddings and birthdays, she added. If that’s the case and she’s not inviting you, find out why.

4. She seems distant
Worry if it feels like she doesn’t “need” you anymore, James said. “If she seems to be emotionally distant lately, if she seems withdrawn from you and unwilling to share even the mundane details of her day when not too long ago she did, this may mean she is cheating on you.” Nonetheless, keep in mind that everyone goes through emotional cycles with ups and downs. Reflect on how long she has acted distant, as short-term distance is natural and can even be healthy.

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5. She becomes possessive of her cellphone
“If she all of sudden keeps her cellphone on her at all times, or hides it, or becomes visibly nervous when you happen to touch it or be nearer to it than her, this likely means there is something there she doesn't want you to find out,” James said. But if she isn’t cheating, she may simply be nervous about something else. Talk with her to see what’s up.

6. Your sex life has changed
A decrease in intimacy could indicate they’re getting their fix somewhere else or are thinking of someone other than you. “Though for a woman, not wanting sex can be caused by many things that are completely innocent,” James said.  If she doesn’t want sex over a period of days or even weeks, her libido may simply be decreased. But keep in mind that moving, getting a new job, or encountering other stressful life changes can also create fatigue and affect sex drive. Ask her if you can do anything differently to fire her up, or, if stress is the cause, see how you can comfort her so both of your needs are met.

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7. She never gets mad anymore
One of the surest signs that your partner has checked out on the relationship and no longer wants to emotionally invest in it is when they don’t get angry anymore, James noted. “If they suddenly take every setback in stride, it may mean he/she is devoting their emotions to someone else.” And yet, she may simply be happy with her relationship with you. For more insight on whether she may be cheating, think about how she responds emotionally to you in all scenarios — not just the ones when she’d previously get mad. There’s a chance her emotional maturity has evolved.

8. She suddenly changes her appearance
“If she suddenly buys lots of new, trendy clothes, and devotes a ton of effort to improving her physical appearance, it may mean that she is looking to impress someone else,” James said. On the flip side, she may be buying new clothes to look good for you! Or maybe she has a special occasion coming up, or there’s a change of season and she’s updating her wardrobe. Talk to her about her motives for the makeover for hints on whether she’s being faithful.

9. She encourages you to spend more time with ‘the guys’
If she suddenly wants you to occupy a lot of your time with your friends, it may mean she wants to free up some time for herself to spend with her lover,” James noted. But maybe the issue is you don’t spend enough time with your friends and wants that to change.

The point is, if you’re suspicious your lover isn’t telling the truth, it’s important to talk with her and find out what other motives may be behind her changed behavior. Communication — but again, in a calm and non-accusatory manner — is key.