I'm going to insert my two cents here.
I don't believe there exists any religious obligation at all about sex, except to not use it as a weapon.
There are a lot of obligations about "love", but that's not the issue at hand here.
In the same passage where Paul talks about not defrauding your mate (except with consent and for a time) he also said "it is good for a man not touch a woman". And he said it was better for unmarried women to remain unmarried.
And in a way similar to Berg, Paul said that this was because time was short and there was so much to do that people shouldn't waste time worrying about their own needs or planning a family.
He essentially said that marriage was sometimes necessary "to avoid fornication" but that (if possible) people should remain unmarried and without sex (like himself).
I think we can safely assume that this was all just Paul's personal opinion, and not "devine revelation".
Jesus never laid down such rules so I assume he left it up to us do decide what to do.
I'm pretty sure He didn't delegate that matter over to Paul's authority.
It's clear that Paul's ideas on the subject never caught on.
But pretending to adhere to Paul's ideas has caused untold suffering in the Catholic Church.
That's why cloistered orders of nuns came into being in the first place. To make a way for Priests to have sex without the world knowing about it.
Over the centuries, and even today in some cases, cloistered nuns have been systematically used as sex slaves by priests, and the resulting children have been killed to destroy the evidence.
And when that practice began to get exposed and stopped, Priests began to turn their sexual drive in other directions.
So I don't think Paul's ideas on the matter should serve as any kind of guideline.
In my opinion, religion has no business getting involved in people's private sex lives.
Sex and marriage are agreements between the people involved.
It is their decision and nobody else's.
Throughout most of history including all of the Bible times, most marriages were arranged by the families. The partners, especially the wife, had nothing to say about it.
Jesus insisted that Love be a part of the personal marriage contract, no matter how the decision to marry came about.
If it is a marriage entirely based on love, that's the ideal.
But if it is in part based on need, whether it be a need for sex, a need for companionship, a need for support, or a need for the essentials of life, maybe it's not the ideal, but it's a still a deal, and nobody else's business. And we are still supposed to love in obedience to Christ's command.
It's sad perhaps if there is not a strong pre-existing personal desire for sex, but not as sad as the tyranny of taking the decision away from the individuals and giving it to some religious authority.
We have all been down that road haven't we?
Sex is not sin. Even when not officialized by the religious seal of approval. It is a natural and necessary part of God's plan for life.
Anyone who tries to use religion to legislate people's sex lives is just another Berg in the making.
Jesus never once condemned anyone concerning sexual matters. And he exposed how "out of it" the Pharisees were when they tried to stone the woman taken in adultery.
He did tell that woman to "Go and sin no more".
But we are not qualified to read anything else into that statement. He didn't say even that to the woman at the well. He knew her situation but he didn't condemn her for it in any way.
I think Jesus tells us all to "go and sin no more" every day.
Marriage is a binding concerning sex and a lot of other things.
Where one partner, for whatever reason, no longer fulfills that agreement, they need to try to work out the solution between themselves.
Leave Paul and Moses out of the picture. Neither of them have any business getting involved.
If the partners can't come to a mutually satisfactory agreement, then the unsatisfied partner has no choice but to make a decision on his/her own. The contract has been ruptured.
Personally, (just my opinion here) if my partner didn't ever want to have sex with me, and there was no valid reason other than a lack of desire, I think it would be safe to consider that marriage was "down the tube" and that it was time to consider other arrangements.
But if it's just a question of one partner having a greater "need" than the other, but not extreme to the point that sex has become a rare event, then I personally would just try to live with it.
Calling upon "professionals" is an option, and I don't think it would be "sin" (even the pharisees would agree with me on that point) but there are other, less risky and more cost-effective means of dealing with excess seminal fluid as well.