IIN that my boyfriend is obsessed with my face?

Go with it. Men can be really sensitive at the glans (head / tip) of their penis so rubbing it on your body would be a wonderful sensation. For you to stop being concerned - why not take control? Ask him if you can show him what you like doing with 'your' cock? Use your hands, don't forget his balls and go to town. Gently, slowly, do all the things at the same speed he normally would but up the stakes. Look in his eyes while you do it. Smile and wink at him occasionally, remember you are the luckiest girl alive :) ask him if he likes that? Tell him how much you love his hard cock on your wet lips. that feels so good baby etc etc. Stick out you tongue and rhythmically 'spank' the head of his cock on your tongue, rub the head around your nipples, gently spank your breasts. Oh and for the gf of the year award use lube or saliva on your hands so he doesn't chafe. When he cums on your face don't forget to say thankyou with a grin. It's meant to be fun so make it so... have him in the palm of your hand lol