Recurring dreams often indicate unresolved emotions or situations in your waking life. In your case, the setting of your college ballroom practice room suggests a connection to your past, possibly highlighting nostalgia or unfinished business from that time. The confusion about the salsa instructor's choice of location could symbolize feelings of uncertainty or frustration in your current life—perhaps related to a project or relationship that isn't progressing as you'd hoped.

The presence of the girl who resembles your adult friend might represent aspects of that friendship or qualities you admire or miss. Her leaving halfway could signify feelings of abandonment or the idea that something important in your life is not fully realized or is in flux.

Dreaming about your friend from college whom you broke things off with indicates a desire for reconciliation or closure. This could reflect your wish to mend past relationships or resolve lingering feelings of regret.

Overall, these dreams could be prompting you to reflect on your current relationships and unresolved issues from your past. Consider reaching out to those you feel connected to or addressing any lingering feelings you have about these situations in your waking life. This may help provide you with clarity and peace.