In long marriages, sex frequency can wax and wane. Certain things can interfere with one's sex drive: kids, health, losing a job, grief over loss of a parent or beloved sibling, etc.
But a partner who starts off sexual and becomes sexless, and refuses treatment (medical), or psychological, sees their partner horny and won't help in any way, for years on end... That person can be dumped, or offered an ultimatum. Willingly open the marriage so I can have sex/intimacy with others, or I am out of here.
No one should be called a pig for having a sex drive. Having a sex drive, even a strong one, is NORMAL. Some will argue it is a need like a need for water, food and shelter. Certainly it is a strong drive that can make you almost crazy (distracted, extremely irritable, losing confidence in oneself as a person...) if unfulfilled.
Personally, I am polyamorous. I have a gf who can be quite sexually fulfilling, but she does go through asexual periods. Luckily my bf is always horny, hard, touchy feely, so I don't have to walk around distracted and throbbing when my gf sits around naked, cuddles and kisses me, dresses sexy, even tells me I am sexy! but won't follow through.
Good luck asserting your needs and desires! You deserve better. Everyone does.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
me: Mags, 59, living with:
miss pixi, 37