India, Sept. 1 -- The loss of desire is one of the biggest challenges that romantic partners have to face in long-term relationships. No matter if they are staying together or apart, sometimes, things fall into a routine, and they stop experiencing the spark that they once did.

Taking to Instagram on August 30, therapist Jeff Guenther explained why that happens, and what can be done about it.

According to Jeff, the number one thing that kills desire in long-term relationships is not any of the usual culprits. It is not stress, or boredom, or just growing old and falling out of love. Rather, it is something that he calls "emotional fusion."

Explaining what that is, the therapist stated, "It's when two people become emotionally entangled...