Relationships end not because you stop loving each other, but because you are unable to feel and then express how disappointed you are in each other and have it spontaneously dissipate and go away
I think a partial explanation why more and more couples are losing intimacy in relationships that they are still remaining in is that they have a great deal of trouble feeling disappointment towards their partner and an excruciating level of difficulty expressing that disappointment. And it's disappointment about anything.
So what people do to avoid admitting and feeling that level of disappointment is either become angry or shut down, both of which eviscerate intimacy in a relationship, cause burnout in a job, or cause depression in themselves.
It really is paradoxical but becoming angry or shut down is not an expression of disappointment, but an avoidance of feeling it.
What's the solution? To first admit the disappointment to yourself, then feel the full extent of it and next, tell the other person. Ironically it doesn't lead to telling them you don't want anything to do with them and it's over as you were afraid it might. The expression of it actually frees you from the pain of holding it in after which it dissipates, goes away and actually enables you to feel warm and good feelings that have been laying sadly unreachable, unfeelable and underneath the disappointment all the time.
Unfortunately the other person might be so agitated as you start to talk that they might cut you off in your expression of your disappointment and say, "Well then let's just get a divorce" before the flood of pus laden hurt underneath drains and enables you to feel that you don't want to end the relationship and never did, you just wanted to end the pain.
Even more unfortunately, it's expecting them to throw it back in your face before you get it out -- which might trigger rage -- that causes you to feel such intense and unbearable vulnerability that it short circuits you and blocks you from expressing the disappointment. And when that happens not expressing it continues to block intimacy.
And what a tragedy that is!