There was a similar thread by another user:
Read some of the advices there. When a woman says no for sex like that at her age and if there is nothing wrong with her physically there is something definitely wrong with your relationship or how she sees you, even though it might seem hunky dory to you (we guys can be a little blind at times to things like that).
For whatever reason (emotional/physical), sex is not as pleasurable for her as it is for you. Don’t think of pheros as a tool to try to turn her on. Been there done that, took a shower in -none and nothing happened!
Regarding phero advice, the biggest realtionship fixer in my opinion is A314 + IS for changing how she sees you.