You wrote:
“And how do we know this? One more time..did Joseph complain to his guy friends ? Did Mary discuss her sex life with the apostles and disciples.. just how do you know this is true?”
She discussed it with God’s angel. Read Luke 1:34-40.
“I thought Mary never sinned”
Right. She didn’t. She followed her vow. She committed no sin by doing so.
If Mary made normal marriage vows to Joseph and didn’t fulfill them, she defrauded Joseph and that certainly would be a sin.