I would disagree with the Jesuit Superior, at least as he’s portrayed here, but for a different set of reasons. Not because modern (not modernist) historical criticism that contextualizes Jesus’ words automatically makes them relative to the culture in which they’re spoken, but because the Biblical context itself defines how the early Church operated.
Virtually all modern critical scholars of the Bible agree that Jesus had an absolute ban on divorce. However, there there is some evidence that the evangelists and St. Paul made modifications to this absolute ban.
In Matthew 5:32, compared with the parallel passages in Mark 10:11-12 and Luke 16:18, the term “except in porneia”, qualifies the notion that divorce and remarriage is adultery (moikeio). While Protestants and Catholics disagree over this term (particularly whether adultery qualifies as porneia – doubtful given that adultery is in the same sentence), the qualification is unique to the Gospel of Matthew. Also, in Matthew 19:29, Jesus commends leaving a wife for his sake. The parallel verse in Mark 10:29 does not include “wife” as a person to leave for the sake of Jesus.
Likewise, in 1 Corinthians 7:10-11, St. Paul reiterates the blanket ban on divorce and remarriage, but on his own authority (1 Cor 7:12), he says in 1 Cor 7:15 that if an unbelieving spouse leaves a believing one, the believing spouse “is not bound” in such cases. The Church has reinterpreted this principle – calling it the Pauline Privilege.
There are others, such as in the Gospel of Luke, which only seems to have the ban on divorce and remarriage, and not the “what God has put together, let no man sunder” found in Mark 10 and Matthew 19. Luke 14:26 also inserts “and wife” into the list of people to “hate” to be a disciple of Jesus, compared with the verse in Matthew 10:37 (which also is a “love me more” rather than a “hate” verse).
Overall, in both the gospels of Matthew and Luke and 1 Cor 7, there is evidence that the evangelists modified the interdiction of divorce by Jesus. Matthew alone suggests leaving a wife, and remarriage following divorce on account of porneia is OK. Luke suggests hating a wife is necessary to be a disciple. Mark doesn’t seem to have any allowance for divorce, and he extends the ban to women as well as men (see Mark 10:12). Since Paul includes married women when he cites Jesus’ ban on divorce (1 Corinthians 7:11), there are multiple witnesses to that being original to Jesus.
The point here is that the Church – in the persons of the evangelists and St. Paul – modified or extended the teaching of Jesus in some way. That suggests, unlike what Fr. Sosa seems to conclude, that there is an absolute ban on divorce in the words of Jesus, but that the Church has authority from its very earliest days to interpret that ban in applying it in its adjudication of marriage and divorce.
With the “Petrine privilege” and the “Pauline privilege,” the Church has done so. Historically, it also exercised its authorities in novel situations outside traditional marriage. It accepted a form of legal permanent concubinage, under Pope Calistus I. The Council of Toledo in 400 accepted that a male concubine of a single wife should not be refused communion. With the decline of Roman civil law, concubinage fell into disuse. In the middle ages, clandestine marriage was accepted as a form of permitted concubinage, though banned by the Council of Trent.