She has no sex drive or is uncomfortable about having sex? Because the two are very different.  

Before I begin I'd like to say that initiating isn't the end of the world. In many cultures women's sexual is frowned upon so even if she wanted it, she may feel too ashamed to act upon it or feel guilty that she is having sex, so.its important to have that conversation first.  

As for helping her feel more comfortable about having sex: 
Initially focus on making her feel comfortable with the idea of feeling sexy. Help her to feel beautiful through compliments, gifts and caressing without expectation of sex or escalation &amp; Help her to feel good in what she wears. 
 
When you do initiate sex, make sure you are your best self. Well groomed and washed. Smell good and looking nice yourself. 


Additionally, boost quality time you spend together. Have you gone on a date recently? Or is  it all just " I do my thing. You do you thing.... now let's fuck" if so, build on your emotional connection. 

And lastly, make sure you're having sex at the right times. Many women report to feeling sexist in the morning or at night whilst men feel it during the afternoon. Ask her and try and sync up  your sessions with her highest point of desire. 

If all else fails, might be time to work on your technique