When you make room in your relationship to honor the possibility of outside attractions and the feelings they create, it can help you stay connected and engaged with each other instead of developing separate lives where you keep your attractions hidden. Being able to talk about scary topics like outside attractions can even help prevent affairs from happening.
On our flight to England, I'd read Mark Doty's Still Life with Oysters and Lemon: On Objects and Intimacy. It is a book about still life pictures, but also about love, loss and our hunger for intimacy. The book moved me, and in the course of a ten hour journey, altered my understanding of why I travel, of why I need to travel.
Relationships are a great place to work on ourselves. There is no harm in trying each of the above steps, as you truly have nothing to lose. The worst case scenario is that you will have grown your own capacity to be loving, vulnerable, passionate and lively. The best case scenario is that you and your partner will grow closer and rekindle your loving feelings for each other.