There are 2 things to lookm into.
1] Low sperm count , where the modern external techniques like IVF/ICSI etc which can work even with 1 sperm can be explored. These days there is a good success rate. However the question remains if they too fail.
2] Low count + low quality of sperms. For external techniques to work, the sperm has to be matured to a certain extent. There are cases where the sperms are below this level throughout its life and so these techniques yield low success.
After exploring various options , the wife can collect sufficient ground for divorce.
Although there is no specific act to support, it would be worth to explore and seek an amendment.