Playing with fire
My best friend is engaged but she's been seeing another man since April. Her fiance has paid lobola - I feel bad
YOUR friend seems to be in two minds about the life she wishes to lead, consequently she is living in two worlds.
You should neither lie for your friend, nor should you tell her fiance. The most loyal thing that you can do is to help the truth come out in the most constructive way possible.
You need to support your friend and encourage her to be honest with herself about her true needs, values and wishes for the future. You need to get the point across that the best time to face this conflict is now. It is easier for a fiance to accept that you no longer wish to marry than for him to find out you were living a parallel life.
If your friend says she wants to have both lives, which is a possibility, then you have to face up to who she is and decide if you choose to remain friends. - Leonard Carr
When you have been asked to keep a secret by someone, which harms another person, you have to weigh up if it fits with your value system and tell the person honestly whether you can become an accomplice in duplicitous behaviour.
The person you need to be honest with is your friend. Be a mirror to her, let her see what she is doing to all these relationships. She is betraying her fiance, the new boyfriend and you.
If she enjoys "playing with fire" in terms of extra relationships, her fiance has a right to know. If she is not prepared to change, you can tell her you will be informing her fiance.
The alternative is that you distance yourself from her. - Stephanie Dawson-Cosser