Have Viewers lost their love affair with the Big Screen?

I think so.
I used to go watch movies about 3 weeks after the movie came out (less crowds, etc.)

Then most movie studios decided to put them on streaming/DVD/Blu-Ray about 3 months after the initial theatrical release. I remember when it used to be 6 months+

So, at least for Disney movies, I've been waiting for them to go to Disney+
For non-Disney movies, I wait for the holidays for them to go on sale.

The last movie I saw in the theatres was Avengers Endgame.

We didn't go watch any of the other Marvel movies (after Endgame) in theatres.

This is the last.

I've read critics reviews that are meh, but friends have all liked it so far.

Yes, we enjoyed it. Sure you have to suspend belief but then that’s true of many movies. It was a fun adventure movie in the same style as the first three, with some nods to the previous ones. Way better than Crystal Skull. 

I didn’t particularly warm to Phoebe Waller-Bridge but other than that I really enjoyed it. The de-ageing effects worked well too! 

Have been off this site for about a month, just catching up now. DH already referenced that I have the AMC A-List. I pay $20 per month, and can go to up to 3 movies per week. I rarely go that often, but 4-6 times a month is not unheard of - and because of current pricing, basically anything more than 2 per month is essentially 'free'. So I've gone to lots of movies that I wouldn't necessarily have paid even $5 or $10 for if it were a separate charge, but have enjoyed many of them. It's not just about the big blockbuster (honestly, I'm getting tired of super heroes, and even starting to be tired of animated and action films). I've really enjoyed seeing a LOT of movies lately based on true events that I didn't necessarily know much about, and learning something (and yes, I realize that I cannot believe everything in the movie, as there is definitely artistic license!). There are some other movies I haven't cared for at all, but I figure it basically didn't cost me anything as I've already broken even, so no big deal.

With our kids in college now, I have a lot more free time (since I'm no longer involved in the parent group of everything they were involved in!) and have enjoyed being able to go somewhere, relax, and just forget about everything else I need to do for a couple of hours. And no dogs or cats wanting attention, or laundry to fold, etc!

I do sort of wonder how things like the A-List get counted in terms of the box office take....

Had two different experiences in the last two weeks. Went to see Elemental 6/25. The film was good, but in my opinion, was not at the level of a theatrical release. We also had an audience of teenagers who decided to have social hour the entire film which was obnoxious. I wanted to see Indiana Jones this past weekend and took my son. Fun film, and the audience reactions added to the excitement of the film. Just need the right chemistry of film and audience to really make it worth while.