1. Zhang Xin is a member of the group, and Eliwa Xu is also a member of this group. So they have the same professional background and experience, and may have gradually developed feelings at work.
2. They once danced a dance together, showing a perfect stage effect, which probably made Eliwa Xu have more affection and recognition for Zhang Xin.
They have the same personality and interests, and may have a lot in common. Such similarities may have attracted Aliwa Xu's affection for Zhang Xin.
It should be noted that the above are only some possible explanations, and the specific reasons may be the most clear to Eliwa Xu himself. Everyone's feelings are unique, we just need to respect their choices and decisions.