Do you this is will be a good topic for my assignment (CELTA)

I've been thinking like for hours and I don't know what to do. I've thought about writing Dear John letter's subject but it might be too fancy for my students. However, I still think it sounds interesting.

Could you please tell me what you think? Specially those who have had an experience with CELTA.

tHANK U

A couple of things:
What happens if one of your students is going through a break-up in a relationship?
Are there cultural considerations? This sort of activity may be problematic in a multicutural group.