I was in this situation for two decades. It was beyond frustrating. My spouse would occasionally indulge my medfet desires, but more often than not, she found ways to criticize my interests, often based on the defense that medfet is out of the mainstream. It caused resentment in multiple ways, both expected and unforeseen. It was part of what caused our divorce.
I agree with all those that say that people should investigate and discuss these issues before marriage, but I also recognize that that is easier said than done, and in some cases, the answers received before marriage can be misleading. I personally find communicating interests about medfet to be even more personal than other sexual desires, perhaps because it is more specialized. Yet I also found that, at least in my marriage, there are limits that are discovered after the “I do's" that remained surprising to me for twenty years.
It should also be noted that we dated for several years before marriage, and had what I thought was great communication, so it's not like we jumped into anything. I would like to say I've learned from it going forward, and that I will do better next time…hopefully so.
I do sympathize with anyone currently in a marriage that is battling this situation. It's hard to want to share something so personal that is then rebuffed (explicitly or implicitly) by someone who you thought was a committed teammate sexually. To those that have worked through these issues, I salute you. To those that are in the middle of it, I send my best wishes. To those that end in divorce, I can say that I honestly understand that terminus now, and I hope you find a partner who understands more of you, or at least is seriously willing to try - even if it takes them time. I am thankful to those on zity who have been open and welcoming.