Mary also said “Since I do not know man”, I believe the different interpretations from the original verse would have some assert she meant she would never know man.
Also, the Orthodox seem to think that God, Jesus, Son of God, came from a sacred place, hence, Mary did not have run-of-the-mill sex after the birth of Jesus.
Apologetics details.
When did conjugal marital relations become something sinful? I dunno...Even Jesus said a man leaves his parents joins his wife and the two become one flesh. I believe 'cleave' was used in the older language. Seems to me a blessing from God not sinful.