Jesus Christ, being married sounds emotionally exhausting.
I just celebrated my 8th anniversary, so I feel like I can speak with some authority on this matter. For me and my wife, marriage has its peaks and valleys (and micro-peaks and valleys within them). There's an ebb and flow in the relationship dynamic that is hard to fully describe, but I think it's part of the human condition to have waxing and waning interest in, well, pretty much everything.
During the valleys (strained, despondent, etc.) marriage is very emotionally exhausting. When we were a new(er) couple, the valleys usually led me to thoughts of divorce, wondering what life would be like without her, wondering what life would be like with other women, etc. As I matured, I stopped taking the valleys personally and understood that they were just a moment in time - one frame in a feature length film. It's a lot easier to identify the root cause of your valley when you don't absolve yourself of all blame and attribute everything that's wrong with your life to your partner. The valleys are few and far between these days because we're attuned to what's upsetting the other and can recognize/resolve the conflict before it comes to a head.
The flip side that nobody really talks about (in this thread at least) is how incredible marriage is during the peaks - especially when your relationship is mature and you're truly life partners instead of a couple of kids playing house. To reach that level you have to be at least a little selfless, accommodating, empathetic, and willing to make permanent changes in your personality and lifestyle. My wife and I have changed a lot over the years. I think the biggest driver of that change was adapting to each others proclivities and pet peeves. We annoy each other less, enjoy each other's company more, and are each other's best friends. Having a strong relationship with someone whom you trust unconditionally is empowering on a level that you couldn't possibly understand without experiencing it yourself. It's fucking awesome.
Anyway, I didn't mean to write a novel. I just wanted to provide a perspective on marriage that isn't often shared here (perhaps because people that are happily married don't browse the thread). Being married and being truly committed to a life-long partnership with someone takes guts, but I think it's one of the most rewarding and satisfying experiences you can have.