The 6 human needs per Tony Robbins are:
certainty
uncertainty/variety
significance
connection/love
growth
contribution
Pretty accurate.
Look at #1 and #2. They're in direct conflict. That means that, yes, humans like certainty. You want to come home and see your house standing, loved ones alive, your job intact the next day, etc. BUT, we also need degrees of uncertainty or BOREDOM sets in.
Therein lies the balancing act. Most couples gravitate too much to #1 over time by default and the relationship becomes stale and boring. Guys usually don't get dumped if they’re charismatic, fun, exciting, funny, etc. They get dumped because they BORING. Ask any hot chick. They crave fun, adventure and excitement. Can Mr. Play It Safe Vanilla Guy provide that? Nope. But too much James Dean, gunslinger, wild man, and the woman will crave some balance and certainty in her life too.
So the key to success in marriages and LTRs is to create a BALANCE between #1 and #2 in a non-dramatic way. Cheating on a spouse and then telling them about it is not the way to create uncertainty. IDGAF does. Having your own life and goals and friends does. Planning some fun exciting, new, and different activities on a regular basis also does. All three should be implemented in any LTR.
Personally, I can do this only so long and A) Boredom sets in regardless B) I get sick of the woman even if she's a HB 9.99 and C) I get tired of all the effort it takes to grow and maintain a relationship at the expense of my own goals and interests as there are only 24 hours in a day.
Good luck.