And what part of that verse says she had any relations thereafter ?
Your reading of that verse is like reading an obituary that says, "Susie had no children prior to her death" and therefore assuming Susie had children after she was dead.
Sorry, any way you cut it there's no proof in Scripture that Mary had other children and given the fact that she accepted the Holy Spirit as the father of Jesus Christ she was therefore already joined with the Holy Spirit and any relations with anyone else thereafter would be adulterous.
Of course, those who take adultery lightly are free to argue whatever they choose to believe based on their faith in their Self and Self Alone which is the only place someone can come up with 99.999% of the trash non-Catholics have to say about Catholics.
have a nice day
Galatians 1:19
19But I did not see any other of the apostles except James, the Lord’s brother. NASB
But other of the apostles I saw none, saving James the brother of the Lord. Douay-Rheims
If read in context there are numerous other passages that tell us Joseph and Mary had other children on their own.
The Greek backs this up.
In Luke 2:7 the word prototokon, first among others, is used in describing Christ.
If the good doctor had wanted to indicate no other children would come from Mary he would have used monogenes, to refer to Christ.
The word monogenes means only, only begotten, unique. One of a kind. Definition from HELPS Word-Studies
I think with Luke being a doctor he would know about how couples have other children and if Joseph and Mary had had other children.