A "rough patch" does not begin to describe what it's like to care for a spouse with a long term physical and mental disability. In fact, calling it a "rough patch" is very insulting.

Imagine the person you most love and cherish gradually falling into a state of decline such that they rely on you for every aspect of their life. Imagine the tearful discussions of feeding tubes, trach tubes, diapers. Imagine part of their cognitive therapy as the ability to count backwards from 10 to zero, and to recite the alphabet, whereas once this exquisitely beautiful angel was writing their masters thesis at an accelerated program at a prestigious foreign university. Imagine years, or decades of dealing with this, and then imagine the heartbreaking loss of physical intimacy, which was once so fucking fierce and torrid that the neighbors would complain. How long could you hold out sexually? A year? Five years? Ten years? And how joyful would your caregiving become as a result of this self imposed repression? Do you think that might create the physiological conditions for resentment? And do you think an occasional self indulgence might make one a more compassionate caregiver? And how about this, in your lover's diminished mental capacity, why don't you try and explain that although you still love them intensely, you need to go get your rocks off once in a while in order to stay sane. While they are crying and feeling the effects of this devastating revelation, you may feel sanctimonious in the knowledge that you have satisfied the "ethical" requirements of the more judeo-xian-islamic tenets of internet judgement.

You clearly have not experienced this. Since I used to see the world as you seem to see it, I will reserve my harsher comments. But you do not get to decide what is "ethical" for anyone not presently residing in your own skin. Much obliged.