It's easy to feel blindsided when an affair comes to light. Few expect the person they love and trust in to betray them in such a painful way.

It's oftentimes only after the relationship has ended that the warning signs seem glaringly clear. Below, people who've been cheated on share the biggest red flags they overlooked.

1. You're no longer having sex.
"When my husband told me he didn't want to have sex until he felt our problems had been resolved, I thought he was being courteous. Turns out, he was sleeping with his co-worker at the time. Long story short: he told me he he wasn't in love with me but wanted to work on our marriage. I tried that for eight months only to find out he'd been in love with his co-worker for months and was just too cowardly to tell me." -J

2. Cellphones become strictly off-limits.
"When someone guards their cellphone with their life, carries it with them everywhere (and I mean everywhere), won't answer calls in your presence and forbids you to even touch the damn thing, they're hiding something. Seems pretty obvious, huh? Maybe, but I put up with it for way too long." -J

3. He or she suddenly needs "space".
"When we started to have relationships problems, I held on, tried counseling and gave her the 'space' she needed. When she told me she'd been getting physical with someone, I began to feel the gravity of things. Before that, I was in denial and believed she wasn't capable of cheating or lying. But there was no way I could lower who I was in order to take back a liar." -D
 

4. You don't go to bed at the same time.
"The one sign I regret having missed is him no longer going to bed at the same time. Turns out, he had an obsession with online cyber sex. I caught him twice in our earlier years but he swore to me he was done and when I followed up he said it wasn't happening any longer. When we finally separated he confessed that one of his cyber 'trysts' had turned into an emotional affair for more than a year. He had plans to meet her when I was nine months pregnant but he chickened out. I divorced him last year. Cheating was only one factor in the decision." - M
 

5. He or she is unreliable and flaky.
"When I dated my cheating (now) ex-husband, he would often cancel dates on me last minute. He was simultaneously very solicitous and unreliable. Burning up my phone to be in touch. Getting together. Making plans. Canceling plans. I broke up with him over it and unfortunately took him back later. The truth is, managing a double life requires a lot of flexibility. If someone is unable to commit to things like coffee or baseball games, dump them. Why is their life so chaotic? People with good character aren’t flaky. Their words align with their actions. I learned firsthand that cheaters dazzle with bullshit, make promises and can be over the top in their affections (love bombing), but their actions tell a different story -- they’re unreliable. Distant. Loving one moment, withholding the next." -T
 

6. Physical fitness becomes more of a priority than ever.
"My ex fathered a child with a friend during our marriage. At the time, he became more of a health and fitness fanatic. He suddenly increased his intake of vitamins. Then one day I discovered the empty bottle of a male enhancement supplement labeled, 'King Kong' lying beside his gym bag in the corner of his closet. Talk about a red flag." -T
 

7. When confronted, cheaters have major outbursts.
"I was with my husband for nine and a half years. As it turns out, he was never faithful. My own internal lack of self-confidence and willingness to put my belief that he was a 'good husband' before all else always trumped my intuition.

The red flag I should have picked up on was that whenever I confronted him about my suspicions, he became angry, defensive and tried to turn the tables on my lack of trust. Instead of talking with me and being compassionate, I became the bad guy. That became a pattern so when the little signs popped up, I began to second guess myself. One night he went to the gym and came home with the gym bag exactly as I packed it. He said 'Oh, I guess you taught me to fold just like you!' Later, his infidelity came to light." -J
 

8. He or she values privacy above all else.
"I was married for 16 years. He never acknowledged me or the children to anyone he knew -- like when the kids were selling things for school, he refused to ask people he knew. He wouldn't even 'friend' me on Facebook and changed his privacy settings so very little could be seen. He didn't know I'd seen the messaging he was doing back and forth with a younger woman." -A
 

9. Business trips become more and more frequent.
"Constant business trips were the red flag I overlooked as a busy stay-at-home mom. There were so many business trips -- and beforehand, he'd gussy up with a haircut, new underwear, even a tanning booth visit before one trip. What makes me ill now is that I would offer to iron his dress shirts, pack him goody bags with his favorite homemade cookies and even burned CDs with our favorite songs for his travel time." -J
 

10. Suddenly, he or she has different interests and hobbies.
"Looking back, one thing stands out. My cheating ex and I went on a trip together to Paris and our traveling styles seemed wildly different. Since we had three young kids at home, it had been ages since we'd had a vacation alone, but my memories were of us enjoying the same activities. This time, though, we were at odds. I wanted to sip coffee at the cafes and people-watch; he wanted to fast track through every landmark and museum. He pulled me along until I had blisters on my feet. I tried not to let it bother me, but it did. We were alone in the city of light and love and I felt invisible." -T
 

11. Accusations are made -- by the cheater.
"My first husband cheated. He would invariably accuse me of cheating while he was actually cheating. It was insane."
-M