OP my story is similar to yours. Knew wife for 12 years and married for 4. Wife, a sweet, gentle person, stated on numerous occasions that she hated cheaters and would NEVER EVER lay down with another man, especially because I was her first and only. After we got married, sex was always an issue with us. Before we got married though, we fooled around at least 3 times a week. But after marriage, 2 times a month was lucky for me. Otherwise the relationship was a great balanced one. We cuddled all the time, and spent a lot of our time around each other. Not many arguments to this point.
She worked very close with her coworker G and disliked him initially (although she talked/complained about him all the damn time) but she eventually "came around" and started being "cordial" with him. Her words.
Weeks went by of her mentioning him here and there. More so than any other coworker, she mentioned this guy. I started noticing little things about her changing. Shaving more often, dressing nicer, working out harder and staying at work later than usual. One evening she was getting ready for a work function which I wasn't invited to. I watched as she left, looking and smelling like pure attraction. When she came back, which was much much later than she said she would, she picked a fight about some really unimportant bullshit. I explicitly remember this because of how insignificant the issue was and how ANGRY she got. I think this was the night he fucked her for the first time.
The days after that were hell. Remember my sweet, caring wife? She'd turned into an uncaring apathetic person. It's like a switch flipped overnight. She didn't give shit about me or my feelings anymore, which in my mind made her look like an asshole. She just wasn't in love with me anymore and said as much during our discussion on where our marriage was headed.
Did some snooping which gave me some evidence that they were in constant contact with each other outside of work. HUNDREDS AND HUNDREDS of text messages, calls and emails back and forth. Why were my text messages and calls going unanswered but this guy was getting instant communication??
I confronted her. She denied denied and denied. Only said that they were friends and although he has feelings for her, she doesn't feel the same. "I would never be attracted to him, he's too short and ugly" she said. lol My sweet wife whom I never caught in a lie was lying straight to my face. Gut was telling me much more was going on. Did a bit more snooping and found out that she was going by his house after work some days while she said she was in the gym. Confronted her again, "No I've never been by his house, I don't even know where he lives." "No, I've only been there once to drop something off". "No it was more than a handful of times but we only talk." "No, I've never touched him and he's never touched me. We are just friends" lol.
I noticed that my life had been COMPLETELY consumed by this drama and was physically and mentally tired. It had been about 4 months of this bullshit and I'd lost so much weight from lack of eating and sleeping. She did as well, but only because she got caught. Stupidly, I believed her and I decided that this marriage was worth it and we decided that we would work on it. She made a complete 180 for a good while. Making more effort to get home on time, giving me more attention, and stopped talking to G, or so she said idk people can "say" anything. She was covering her tracks well.
Couple weeks later I got an email from someone I still don't know. I think it was his girlfriend or at least someone that was close to him that wanted to hurt him. It was screenshots of his phone with tons and tons of messages to her. Talking about their favorite positions, about where they liked to fuck, how she loved swallowing his cum and having it on her face, (SHE WOULD NEVER EVER LET ME DO THIS), about how he ate her out, how she gets wet at work just looking at him, about how she was sorry that anal was too tight and she wanted to try it again (ANAL WAS OUT OF THE QUESTION IN OUR MARRIAGE). Also about how she has to lay low for a while because her husband was on her back.
My message to you is don't focus on what she says, only what she does. People are honest when they don't have a motivation to lie. Your wife has a VERY big horse in this race and has all the motivation in the world to lie to you. How much time did they spend in hotel rooms and on the road? She's been fucking this guy for a long time. You can only say no to temptation for so long OP.
Tread very carefully.