help! how can i make my partner cum?

please bear with me. this is my first time creating a reddit account and ever posting one.

a year into our relationship and i’ve always had a hard time making my bf cum. he already told me before we even became official that he’s a very vanilla guy and rarely do masturbate. that’s fine with me and most of the time, i’d be the one initiating things but ever since we started, i’ve never made him cum by myself. i’ve tried different things i can think of – searched through the internet, try and watch porn that i think would be pleasurable for him, stimulate his certain body parts, tease and build up tension.. literally anything i can think of but the ONLY way he can cum is through missionary style penetration. he already made me cum multiple times and i think it’s unfair on his end that i can’t give him the same satisfaction.

one thing i can think of is to try and replicate how he masturbates – by using his thighs and twisting? or squeezing his dick on it. i tried searching it up and it’s called syntribation (?) i’ve read multiple threads about it here but it’s mostly for women. do you guys have any idea on what i can do to mimic the same pleasure or any position, action, or anything just for me to reach the desired goal?