ISB ~ Matthew 1 v25

until:The Greek heos does not imply that Joseph and Mary had marital relations following Jesus’ birth. This conjunction is often used (translated “to” or “till”) to indicate a select period of time, without implying change in the future (2 Sam 6:23 [LXX]; Jn 9:18; 1 Tim 4:13). Here Matthew emphasizes only that Joseph had no involvement in Mary’s pregnancy before Jesus’ birth.

• Mary’s perpetual virginity is firmly established in Church tradition. Its doctrinal formulation is traced to the Lateran Synod of A.D. 649 and was reaffirmed in 1968 by Pope Paul VI (The Credo of the People of Cod, 14; CCC 499501).