Verbalizing isn't for everyone, and it's better to be clear in a letter than confused and jumbled out loud.
People can, and do, use letters to communicate difficult issues throughout their entire relationship. It works for them, so just because your preferred method is the spoken word, doesn't mean it's the only effective method.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker