So confused

Me HLM 48 and her LLF 52 have been married for 15 years and have 2 kids. So we haven't had sex in at least year a year and I would guess the previous 3-4 years we had sex maybe 4-6x a year. I setup a counseling session for us and the counselor gave us some tips and reading she didn't do the reading and things slowly went back to the way they were.
In the past year we only talk about the kids and I realized she has no interest in having sex with me, she was only doing it out of duty before. That killed my interest in her, add to that her hobby is criticizing me and you can see why I want to keep my distance.

A couple of friends invited us to a vacation together and since we all have kids of similar age I said yes and had this vacation booked months ago. Now my wife is not a social person, she doesn't like to visit friends and she doesn't want them at our house, her favorite activity is to sit on the couch and scroll FB for hours.

We went on vacation and a different person showed up. Gone was the distant person who would respond to my questions with one word answers, one time the week before the vacation I was talking about one of our kids and mid conversation she just walked away. Shocked I awkwardly said well that was nice and she came back and said she had to go to the bathroom. This new person was outgoing, fun, exuberant, she wanted to go running, do sports. Even the other moms were looking at her like what is going on ?

I had no idea what to do, I didn't want to be a dick and ruin the vacation so I went with it. She kept planning things even the kids looked confused. We had a very fun vacation, I remembered this was the person I had dated before we got married, it bore no resemblance to the person I had been living with the last 4-5 years. She even tried to initiate sex one time, I told her I was too sunburned.

Now we are back from vacation and the vacation person is slow disappearing, yesterday morning I tried to talk to her about something she pretended she couldn't hear me and after waiting 30 seconds I walked away.

But now she's active around the house, for background I do almost all the cooking and shopping. I once asked her to cook 2x a week and she can barely do that. Since we have been back from vacation she's been cooking every night. I asked her how come and she said I was making her do it ??? I said how ? she didn't answer.

Has anyone gone through something like this when your partner suddenly switches personalities ? I wonder was she pretending before we got married and then I saw the real her ? or is it she's worried we will get divorced ? I am totally bewildered here.