Tongue tied boyfriend won't do oral because its "difficult"?

I'm all about making him feel good, we both have high sex drives and I do enjoy giving him blow Jobs, like all the time, I'm comfortable with swallowing (I'd rather not, but since he likes it, it kinda makes me want to so I do) I get pleasure by seeing him pleasured and enjoying it. However, I feel he hasn't really reciprocated as he's never gone down on me with oral. I've also never orgasmed with him. I've researched it and I've seen people say it makes no difference because instead of the tongue you just move your head a little, he's fingered me and LICKED , I repeat licked, downstairs once, like 2 months ago, we've had oral + sex multiple multiple times since then. I finally said again today "I have an idea of what we could do" and played with his lips a little and he said "thats difficult for me, you know I'm tongue tied" when he's never actually tried. I know it's not mandatory and if someone doesn't like something sexually you shouldn't pressure them.. but I feel I'm doing all the giving here. We were intimate today & we always do doggy style that's what he likes, I was like hey lets do missionary, he said let's do riding because he's tired. I don't know how to communicate the message accrossed I'm not feeling satisfied without sounding ungrateful/mean. Help?