Sometimes, when you're deep in a relationship, you can miss (or ignore) signs from your partner about the things they could be doing behind your back.

So, when Reddit user u/missgill_ asked the question, "What was the one sign you didn't catch while being cheated on?" In r/AskReddit, I knew the comments would be full of astonishing behavior:
1. "I had an instinct that something was off. Nothing tangible. I remember he came back from working abroad for a week, and I said to him, 'You seem different somehow.' Well, he’d been in a hotel shagging some woman — there were no visible signs, just something…off."

2. "My best friend at the time seemed to go from being super awkward and quiet to extremely cocky and specifically belligerent towards me. My partner at the time was spending a lot of time with him (we were part of the same larger friend group, so it never really seemed weird), and it just never added up in my head. I ended up being the one that got shunted out of the larger group despite being the victim."
3. "The biggest sign I missed was his sudden need to spend more time apart, claiming he had plans with 'the boys.' Turns out, it was actually another girl. Besides that, I (stupidly) ignored other red flags, like him hiding his phone, finding Hinge on it, and discovering he had a secret Instagram account where he was only following one person — yep, the other girl. And, for his birthday, he told me he didn’t want me to be part of the celebration."

4. "He always accused ME of cheating, even though I had done nothing to make him believe that, and he kept constantly telling me how being cheated on was his biggest fear. He ended up cheating on me with multiple girls throughout our relationship."
5. "I think I knew, and it wasn't just one thing. They would spend a long time on the phone, sometimes the whole day. Sleeping in the other room 'to get better sleep.' The little smile you see when they check a message and the speed at which they're checking them. When you open a door and suddenly the volume of a conversation drops, or it switches to just typing. I saw all of it, and I chose to ignore it, as I see myself as a jealous person sometimes, and maybe I was just being paranoid."

6. "She started sleeping in another room because of my snoring and then sleeping in later. I thought she just needed better sleep. Really, she was staying up all night sexting the other guy."
7. "I brushed off how 'buddy buddy' he was with our roommate (my best friend of 11 years, and a proud lesbian, or so she thought). She’d come into our room to hang out, and by the time I awoke in the middle of the night, they’d be on the ground together, close and always touching one another in some way. I thought it was just friendliness! Until I caught them making out."

8. "In high school, my girlfriend and I worked at Six Flags in the same games area. All of a sudden I started losing hours, and she started getting overtime, always closing with the same games lead. Then I started getting scheduled to close on Saturday nights, and she and the lead kept having Saturdays off. Good riddance."
9. "Constant napping. We were long distance, she was a chronically tired person, and she was on a depressive stint, so I assumed she needed the sleep. I found out far too late, once the lies stopped adding up, that there was something else going on. Looking back, I should’ve realized it when the naps started ramping up and our time together was interrupted at every turn for a little sleep."

10. "My ex didn’t want to have sex for a while leading up to her girls trip because she hadn’t shaved down there, and then the day she left for her trip, I walked in the bathroom when she was getting out of the shower, and she was freshly shaved. I always had suspicions about those trips."
11. "She would come to my house after work and immediately want to take a shower (she worked in an office). That, and she’d have random bruises sometimes on her legs, and when I asked about them, she said she must have bumped into something at the gym."

12. "She suddenly became weirdly supportive of me going out with the boys. Like, not just okay with it, excited. I thought she was just being chill. Turns out, she was scheduling my 'fun nights' to line up with hers. While I was out drinking, she got pounded by her coworker."
13. "He always wanted to know my location so that I never crossed paths with him and his side piece. His friends started giving me weird looks, like they felt sorry for me. They also started to be nicer and more gentle with me instead of teasing or joking. The atmosphere was suddenly serious."

14. "My best friend of 10 years cried on my shoulder multiple times in my house. I knew it was about a girl, but he didn't want to give any details. I told him I'm always there if he wants to talk. Turns out he and my wife (who was my caregiver through chronic illness) were making plans to run off together. They're married now."
15. "Oh god, everything. I was so blind and stupid. He talked his way out of everything so casually. Socks in our bed, long blonde hair on my pillows, shampoos that weren't mine, work schedules — he had an answer for everything. This man was living two completely different lives, one with me (gay) for eight years and one with his girlfriend of two years. I've never in my life been through the hell that man caused me."

And finally, in a turn of events, here's a hot tip from a cheater to let you know a sign you should definitely be on the lookout for:
16. "Every time I’d finish with my mistress and come home to my poor ex, I would be overly loving. Not the normal amount of appropriate affection; I would really make sure to go the extra mile, really make sure she knew how important she was to me."

Was there a sign that you missed from a cheating significant other? Let me know your stories in the comments.
Note: Submissions have been edited for length and/or clarity