I do not know how your friend did it exactly, but my main experience with people who are into astrology is different - they get told by the astrological models/dogma on how to think of people and combination of people.
"I cannot be with this person, he is a lion and I am [whatever]"
"Why are you together, your signs do not match each other"
In other words, they "help" by simplifying things. Avoiding thinking to make decisions. But in my experience that always hurt them in the long run. And it probably destroyed many relationships as people went with the simple astrological explanation, instead of a real analysis what went wrong. Or rather, it often went wrong, because of negative self fullfulling prophecy.