Desensitisation due to various factors, namely porn I'd say. Plus media, staleness, age, over exposure, distorted viewpoints or expectations, social stake etc

There's only so many times you can look at t and a before staleness enters like repeating the word apple until the letters feel meaningless

Since sex is mostly entertainment and recreation now, and the modern age has ramped entertainment into the extreme, sex kinda becomes outdated and antiquated, even

Particularly compared to other stimuli and entertainment, the endless options at your fingertips, the opportunity costs of sex are far greater than before modernshit times, so much shiny trash competing for your attention

Now that everything's out in the open, the mystique is lost and again, staleness

I prefer erotica to just sex. Sweeping, weaving narratives so sex is an amazing reward, rather than just merely sex.

Some common issues when it comes to sex in the modernshit times, including but not limited to r-
There's Lotsa FOMO due to media, overhyping, pedestalising, etc.
Then there's relationship tensions/other tensions due to sex being part of one's self esteem and self image self worth and feeling unattractive and blah
Then there's anxieties and not being able to even do the deed itself due to mental blocks
Then there's just libido, some people need that sweet release, perhaps they're stressed and need some temporary respite and the familiarity and safety of the sexual setting and orgasm provides this certain structure, just 1 more orgasm and then I'll fix my problems procrasturbation style

It's just sex, okay! Just stupid dick insert to vagina thrust thrust cum fertilise egg

Previous ages n eras there was no birth control, no paternity testing, hence virginity (chastity, restraint) and not being a whore was much more.. Important?
Now being whorish is rewarded (enabled, celebrated, encouraged)
Sex ain't that special or rewarding anymore

So go do something else