Excellent read!

I myself am not against having a single partner for life.  
I like to think going against what "nature" tells us is natural, defines who we are as the dominant species.

It's unrealistic to think one person can satisfy all your needs ( emotional, spiritual, sexual, intellectual, ect) for a life time.  

Some studies think more women may be cheating than men, women are better at deception. It's all about opportunity & options.

at what point is it just attachment because of years together and no longer love...?

I'm as loyal as my dog!

At this stage  of my life, as long as I'm treated well and fed what I need,
 I feel  no compulsion to stray.
 
I'm accustomed to cooking and  thoroughly enjoy pleasing my Gal's palate, therefore  she has no need to work in the kitchen preparing my food, to keep me as faithful as my dog.  

  Everyone's different, I suspect the variety and abundance of Gals I could easily find in my youth, whether I was already in a relationship or not, allows me to be comfortable and satisfied with one Gal at a time now that I've found  my more mature years.
   
I actually feel bad  about some of my GF's  I cheated on in my youth, even a few of them that  never found out how easy I was behind her back.  
   
     Fortunately for me,  I've never been the moping type of guy who withdraws from relationships after  a great relationship  goes down the tube.
 
    I'll admit  if my GF decides she wants to move out tomorrow, I'd likely pay for time with ten different Gals before New Years, hoping to get over my loss as quickly as possible.
   
As she  stands today, I wouldn't trade her for any ten tens.  
   
   Later,  I have a quick and easy Spaghetti Carbonara  and Kale salad  to prepare before she gets home.  
  Fortunately I plan ahead, I started my home made bread late last night  
                  after she fell asleep.