Many countries allow two people to marry without a residence requirement. So you have three choices:
- Marry in Pakistan and then sponsor him for permanent residence (outland)
- Marry in some fourth country where there is no residence requirement for marriage (or a short one), such as any number of European countries, and then sponsor him outland
- Submit a “conjugal” sponsorship application wherein you claim you are unable to get married because
- He has been denied a visa to Canada four times
- You were prevented from marrying in Dubai.
Note: the third option is extremely difficult and they will wonder why you didn’t marry in Pakistan and may reject the application on those grounds.
His application has likely been rejected because they are worried he will stay in Canada once he travels here. He has likely not provided enough proof of his ties to Dubai.