couldnt cum as a guy? help

i literally had fucking sex for over an hour and then got head for even longer from my SO. is it because i dont like woman or am i chemically castrated from my SSRI? lol (i take lexipro) we both were super into it and they came like 7 times but i couldnt. i had already jerked off earlier that morning could that have had an effect? im young just to clarify