There are two aspects to consider here:
Firstly, this is not how true Satanism works, requesting something without effort or reason will not lead to meaningful results. It's crucial to understand that if you desire something, you must put in the work to achieve it in some manner. Having said that, what you can ask Father Satan for is guidance in comprehending how to pursue your objectives and fully grasp the ramifications of this particular situation.
Secondly, it's highly likely that there was a valid reason for the breakup between you and her. Perhaps she didn't deserve your time, or you didn't deserve hers. Take some time to reflect on it. Explore areas where you can improve yourself. Engage in introspection and try to understand what went wrong, and how you can surpass your limitations or any faulty decisions you made, if such was the case.
You don't need divine intervention to be able to seduce a woman, as a man you absolutely must be able to do this on your own.
The fact that she "is" xian doesn't necessarily mean anything. She doesn't have a genuine understanding of what xianity truly entails. As long as she isn't an extreme and potentially harmful fanatic, you can pursue her if that's what you truly want. You have to show her that there are healthier ways to live life and that you can add value to her life in this regard.