"For Your sake I bore disgrace; humiliation covered my face. I am become a stranger to my brothers, an alien to my mother's sons; for the zeal of Your house consumed me, and the insults of those who disgraced You fell on me"Whereas a Psalm can be considered prophetic of Christ, prophecy was not the primary purpose of the Psalms. For instance, this passage from Psalm 68 was not written to speak directly of the future Messiah; rather, it was written primarily to speak of issues the psalmist faced while he was writing the Psalm. We see in this Psalm imagery that we also see to some degree in Jesus Christ, but that can't be seen as proof of any position for or against Mary's ever-virginity.
Psalm 68:8-10, Orthodox Study Bible page 726
I understand what you're saying, but would have thought that prophesy in relation to the Lord was as primary as any other purpose of the psalms. The quotation I have given is all related to Christ. We know the zeal of God's house consumed him - John 2:17. This is absolutely a direct prophesy.
We know also about the disgrace, humiliation and insults he endured. They called him a glutton, a drunkard, a blasphemer, a Samaritan (a dreadful insult, apparently), claimed he operated by the power of Satan, and was in fact possessed of a demon. Finally they had him nailed to the cross, a death of shame and total humiliation. I can give you scripture for all of this, but know you probably believe it.
We also know he became a "stranger to his brothers", in that they did not believe him - John 7:5. In view of this, I can't see why the thought of becoming "an alien to his mother's sons" should not relate to him as well. It's a big ask if that's what you're asking me to believe.
Anyway I was just reading the psalm the other day, and wondered what the perpetual virginity people thought of it