We are sort of like friends...that do a lot of flirting...but I don't understand the behavior now

It was initially one sided flirting on his end for a long time which was eventually reciprocated in small ways initially. Then he started sending dick pics which almost ended the "friendship" but because a lot more common when it was better received later. There was an episode of sexting that then resulted in an almost immediate decrease in how much we communicated (I normally let him initiate most of the communication). From early he had asked for casual hookups, and much later down the line I agreed to it, but something came up the last couple of time we were supposed to. Finally sent him a lingerie pic (no face or background was in the pic) that he had been asking for since he first sent me a pic of himself...but since then he has been even more quiet. The last couple times he tried contacting me was literally to see if I was free to hook up...but we haven't actually hooked up at all. I know this isn't anything serious but is he just trying to see what I will agree to?