One of the leading causes of breakups is a lack of understanding of someone else's likes and dislikes.
Your ex doesn't like sex. She told you but you insisted you want the two of you to have sex since you like it. You were forcing her to do something she wasn't ready for or doesn't like it.
You should have sat down with her and talk about sex. How will it be during marriage? The fact is that she won't engage in sex frequently (daily). This is something you should have understood.
For instance, I don't like sex but my other significant loves it. I told her I don't like it though she insisted she likes it. It causes conflict because it is forcing someone else to engage in something she doesn't want although to you it will translate as being denied your rights.
This is the reason why it is important to talk things through before getting married.
If you want her back and are satisfied with doing sex with her occasionally; you should apologize to her. You can contact her through call or text and explain how selfish you were and have repented of your lack of judgment and understanding. You should let her know you're comfortable with having sex occasionally.
If you're not comfortable with the idea of having sex occasionally, you shouldn't bother her. You should respect her decision. You should look for a future wife who you can engage with through sex on a daily basis.
People should remember not all of us love the act. Some love it to a minimum level while others hate it.
Lack of satisfaction in bed or not engaging in sex is another cause of divorces. It's up to partners to discuss sex before getting married.