If that man could not be accompanied by her as his wife, being the only person in this world who shares the same bloodline with him would still be a matter of pride and happiness! Why would she leave then?
She couldn't let Feng Cang go. If she couldn't be his bride, then she would be his sister for life!
The poison and Gu within Feng Cang haven't been removed yet, and their common enemy is still alive and well. The great vengeance hasn't been avenged, so if she just leaves, where would that place Feng Cang? What would he do?
If the two of them really couldn't be together forever, then she would protect him and watch him be happy. One person being happy is better than both of them being sad! At least, if he is safe and happy, then she is happy too! To love someone means to hope for their happiness, doesn't it? She loves Feng Cang, so she must protect his happiness!