so instead of telling your partner you don't enjoy the sex as much as you could, you basically just didn't have sex as much, and masturbated. leaving him with a crippling sense of crushed self esteem.

i did the same thing to my ex when i just stopped banging her and watched porn all the time. i understand her rage and frustration now, cause it's a shitty thing to do. when you're in a relationship you're allowed sex with one person, and you really love that person and are attracted to them (or you should be), when that person just says (lol nah) and you still see them clearly engaging in their sex drive, only without you, well, its a kind of soul crushing blow i wouldn't wish on anyone.

go see /r/deadbedrooms to know how your ex boyfriend felt. you likely destroyed his self esteem for a very long time and made his sex life suffer in every subsequent relationship, due to his utterly annihilated sense of sexual self esteem.