Matt. 1:18-25 – Verses 18 and 23 show the context of the passage. Matthew clearly speaks of Jesus’ birth and concentrates on the fact that he is born of a virgin. His intention is not to state that Mary had sex after giving birth but instead to declare the virgin birth.
Other Passages using the same manner of speaking –
Matt. 28:20 – Does Jesus cease to be with us after the end of the age?
Acts 8:40 – Did Phillip cease preaching after Caesarea?
1 Tim. 4:13 – Did Timothy cease to give attention after Paul arrived?
2 Cor. 3:15 – Does this passage mean that after that day there is no veil?
Luke 1:30-34 – Why would Mary ask this question if she was planning on marrying and having sex with Joseph in a short time? Mary seems incredulous that she could conceive, and the Angel does not rebuke her as he did Zacharias.