What is to be understood from an istikhara whose first vision indicated engagement, while emotions became mixed after the second?

We have no knowledge of dream interpretation. The preponderant view is that one who performs istikharah (prayer for guidance) should not rely on a dream, or on a feeling of comfort or discomfort. Rather, one should proceed with the matter after istikharah, unless Allah diverts them from it. Istikharah should be performed when one is concerned about a matter, not before it. This means that if a suitor proposes to you, it is legislated for you to perform istikharah concerning him. If the man has not proposed to you, then you should divert your heart from becoming attached to him and occupy yourself with what benefits you. It is permissible for a woman to offer herself in marriage to someone she sees as righteous, provided certain guidelines and etiquettes are observed.