Sex and Marriage

I need help!!! I don't know what to say. I need more sex in my life but don't know how to tell my wife I need more. It doesn't seem like its as important to her than it is to me. I already told her many times that I need more and she says she'll try harder to make it happen but it doesn't. I don't know if it's because she's had more than me or what? She's my one and only person but I'm not her first. She's had others before me. I'm so 😳 worried! I keep reading online and it says that problems with a sex life can lead to many more problems and eventually divorce. 
What do I do?