Meh. I've had enough about baiting the church. Hint at a couple of saints being lovers and they'll scream hellfire at you for being 'revisionist', notwithstanding that revisionism has a looong history in the catholic church.
And yes, marriage was first and foremost to create heirs. The greeks especially married simply to bear sons (and avoid daughters, so they won't have to pay dowries). They still pursued homosexual relationships quite readily when available and in practices of pederasty. You can see examples of this in mythology, where the hero has a wife/damsel-in-distress while still maintaining a trusty shield-bearer/squire/male lover on the sidelines. Hercules is a prime example, having had relationships with both men (Iolaeus and Hylas) and women. They kept homosexual and heterosexual relationships separate - the former a matter of passion, love, and male friendship; the latter of passion, love, and marriage/reproduction/and even work. In most cases, men were for pleasure, women were for work
. With certain exceptions like the elite warrior group The Sacred Band of Thebes
who were composed of 300 purely homosexual warriors and had no need for wives to maintain their status in Theban society (Interestingly, modern Greece, one of the most homophobic countries in the modern times, still honors them. They were finally defeated during Phillip II's invasion of greece, when they refused to retreat when all their allies had and died fighting the much larger macedonian forces. The site of their graves has a lion statue as a memorial to their courage).
Celts also had the same thing going. But unlike romans and greeks (and middle easterners as well including semitic cultures) whose women were little more than house slaves, their society was much more gender equal, even leaning towards women at times. Men also slept with men, and married women to sire children, and it was no big deal.