I'm sorry about what your son is going through. Unfortunately, things like not having sex or putting your spouse down are irrelevant for purposes of alimony. When the court awards alimony it is usually to provide support for a spouse who did not work for years and has a diminished earning capacity as a result of not working. Your son can challenge or appeal the court's decision, but until and unless the court's order is modified, he will owe the alimony to his ex, and anything he does not pay will accrue as past due alimony. It is also unlikely that your son will be able to get the court to change its decision unless there is a change in circumstances (i.e. if your son's ex gets a good paying job, if your son's earning capacity is diminished, etc.)
If your son doesn't pay the alimony, there is a possibility that he could be put in jail. This usually doesn't happen, but it is possible. The court can also do a number of other things like take away his driver's license, hunting licenses, etc. The alimony can be withheld from his wages if his ex gets a withholding order, it can be taken out of his tax returns, etc. And, the past due alimony will never be able to be discharged.
Is the alimony temporary or permanent? If the alimony is temporary, it will end upon the date set by the court. If the alimony is permanent, it will likely continue until your son's ex remarries or gets a job which pays enough to justify ending or modifying the alimony.
Please let me know if you have any other questions. If this answers your question, please click "accept" so I may receive credit for my answer.