My simple answer is YES.
Love fades. No matter how you nurture it, nawawala pagdating ng panahon. And not because of the many valid and reasonable justifications, kahit na walang isyu sa inyo whatsoever, kumukupas lang siya talaga.
Then you start longing for it, for that feeling of being in love. And even without actively looking, darating na lang bigla and before you know it, you have become involved.
I am not saying it is right, of course, mali talaga ito in so many aspects. Pero you can't stop the feeling. What you can do is manage it, choose not to act on it and keep your current relationship alive. But it does eat you alive, kahit na alam mong tama ang ginagawa mo, there's that feeling of emptiness, of emotional fatigue, that just keeps gnawing at you.
Mahirap. Super hirap. Whatever direction you take, someone's gonna get hurt. There is no real way out. There are just detours.