I think the best thing I've read about this was a theory by Robert Sternberg I learned about in a developmental psychology class I took. I posted it long ago.
According to Sternberg relationships consist of three key components.
Passion: is like lust, a combination of attraction and sexual desire.
Intimacy: is a closeness, sharing, and bonding between people, sharing your thoughts and feelings.
Commitment: is the decision to remain with another person long-term, and commitment to keeping the relationship alive.
The combination of these results in the 8 types of loving
Non Love: None
Friendship: only intimacy present
Infatuated love: only passion
Empty love: only commitment
Romantic love: Passion and Intimacy
Compassionate love: Intimacy and commitment
Fatuous love: Passion and commitment
Consummate love: all three
I don't think love is static and we can bounce around all types of these loves in relationships.
There are times we can love the other person but not like them, times we don't feel attraction, times we don't feel that close intimacy.
I think the problem is if we remain in an "absent" state too long (one or more key elements missing).
This, to me can be true of any relationship.
A relationship that has experienced infidelity has had all three elements blown out of the water. It's one thing to "miss" an element, it's another thing to now have pain attached to all these key components.
How can you feel passion when it's now clouded with thoughts and images of your spouse with someone else?
How can you feel intimacy when a key component of intimacy is vulnerability and being vulnerable to someone that's hurt you so horribly is an almost impossible task.
How difficult it must be to feel commitment as well. I would honestly think having a strong moral code and self preservation is sometimes the only thing that keeps commitment even in the picture for many BS's.
I asked for a definition of what it means to be "in love" but he couldn't really put words to it.
He may not honestly know right now
(((bewuzzled)))