Trust: the belief that someone or something is reliable, good, honest, effective, etc.
Trust is an integral part of any relationship but the amount of trust needed behind TTWD is way beyond basis trust.
TTWD makes us vulnerable.
TTWD can be rapidly destroyed by a single breach of trust.
One may try to forgive and move forward but once broken it can never be the same again.
In TTWD we share our soles, we reveal our deepest secrets, share our wants and needs, bare our bodies, submit to our Dom's, trust them to spank us, restrain us make us completely at their mercy. I do believe TTWD is one of the biggest displays of trusts there is.