She is overly compliant. She fears rejection, her sense of self is based mostly on other people's opinions of her. Sounds like she cannot regulate her own self worth, leading to low self esteem and an inability to recognize what she wants out of social interactions until after the interaction has concluded. Hence the regret.
It may be indicative of past abuse, in one or several of the many forms in which it can be experienced.

I am extrapolating, and speaking from personal experience. I may have wrote it 'matter of factly' but it is just a suggestion.

My advice for her would be to pay attention to what her body is telling her during these social interactions, our bodies can tell when we are putting ourselves in a situation we are not comfortable with or do not wish to be a part of.
It comes many forms. Sudden anxiety, a heaviness in the gut. acute sweating, goose bumps, etc. Be mindful of the decisions you make, try asking yourself if this is something you want to do, before you do it.