Hi I understand the issue. Many factors can lead for this situation from her side. First we need to understand those reasons too. As Male & Female bodies are biologically different, it will not be the same feeling for both the partners.
A detailed case taking is necessary to understand the reasons in clarity & to tackle the situation either in the way of medication or by proper counselling.
Next Steps
Feel free to consult online via Practo
Health Tips
Spend more quality time with her
Give compliments wherever necessary