My wife and I are both 55 and have been married 26 years.
For over ten years she has worked for a large national retail company.
This May she told me she was joining a women's group consisting of current and former employees. She said it's a support group that also does various social functions and outings.  That is great I tell her. It should be fun and relieve a lot of stress.
Then the red flags started popping up.
In June I noticed she locked her phone and didn't offer me the new unlock pattern.
She has never locked her phone on me. She would always fall asleep with the phone in her hands. I would go in and close all her apps and make sure her alarm was set so she'd wake up on time.
Now that it was locked I noticed she was more "protective" of it. Like if she was asleep and I tried to put it away on her nightstand she'd wake up and snatch it back saying what are you doing.
By July I knew something was up with her. She became obsessed with the women's group.  She even took a weeks vacation and spent it on various outings with them.
A few times she even took overnight trips but she would never tell me in advance.  She seemed vague about her plans. She'd only feed me piecemeal info. Later when I asked about it she would say I didn't listen. But I said you never told me any details.
In fact whenever I asked her about her plans she was now saying I was "needy" and should find my own group of friends to hang out with and basically to let her have her freedom. She said I was having a "mid life crisis" by fawning over her all the time.
In August she asked my teenage daughter and her friend to help her women's group with a flyer for an upcoming Fall tea dance in September.
I Googled two of the sponsored groups on the flyer and discovered they were clearly lesbian groups in Meetup. WTF!
I also found out what "tea dance" really meant. What a naive schmuck I felt like.
So now I questioned her about the nature of the women's group and did she know they were a lesbian group.
She kind of skirted around it and said most of the women are from the company. Some of them are not even lesbian, they have husbands like her.  I said surely the leader of the group Mary must be a lesbian. She said she wasn't sure. She knew Mary was divorced before but not sure about the lesbian part.
So she is stonewalling me for a few more weeks and she is still vague about all her social outings.
I'm worried about our marriage and so start snooping and spying. Between her printed time sheets, access to our cell phone account and access to her Google account I find out some things.
I have been keeping a journal since June and now I start to backfill it.  She has been secretly seeing Mary and concealing it from me by not saying where she is or even lying about where she is. A few times she'd take a sick or personal day and not let me know.
Google will pick up dictated messages she makes for texts and she has been using terms of endearment with Mary.
i.e. "okay love goodnight I'm home."
"good morning love. just got to work"
"see you I am on my way to you now love"
"hon I'm leaving now I'm going to get gas I'll come over to your house"
"hey babe don't be mad"
"hello Mary don't be mad"
"hello Tina my baby is mad at me. I'm trying to do too many things at once."
"you are right I was wrong I was trying to do too many things at once"
"I should have called and let you know and I was wrong with that"
"I am really really really really really really really sorry"
"I am on my way to you love"
"who would ever thought that Mary will be at the Victoria's Secret"
"she is choosing" "she like the leather" "she like the lace"
"good night love I had a great time today sweet dreams"

We actually went on a 3 day anniversary getaway this week and it was good.
If I wasn't spying and snooping I wouldn't know about her "relationship" with the 79 year old leader of the lesbian group. She is basically leading a "double life" and thinking I'm ignorant.
On the night we came back from our trip she actually went to see Mary which I found out about.
I showed her I knew about the messages and asked her why she was hiding from me the time she spent with Mary.
I said I was angry, hurt and confused and very worried about our marriage.
She didn't really address anything directly.
She said Mary was a "sweet old lady" that she liked to talk to.
Everyone used those terms of endearment with her.
I told her I was going to see a therapist and she was surprised and said "why?"
I said I need to work some things out for myself and I'm really worried about us and our marriage.
I'd really like you to go with me to see the therapist.
Surprised she said yes so I'm trying to set up the appointment before she changes her mind...