Having organs doesn’t mean they would have to be used, and you still can’t do away with either polygamy, which would hardly seem plausible, or ‘friendzoning’ of all of one’s former, earthly spouses minus one, which would hardly seem fair.
In my opinion it would be wise to presume God made them man and woman, one man and one woman, at the beginning, before men corrupted this, not just for the earthly sojourn. It would appear strange for God to make a point of creating a monogamous couple just to allow polygamous sex in heaven.
As for Adam and Eve, intense pleasure does not necessarily have to include an element of passion. At least passion the way we understand the word. And certainly not concupiscible passion the way Aquinas understood the words.
Still, I don’t find convincing reason to believe there must have been intercourse in Eden. There is not record of any children at the point of expulsion from paradise. And sex is for procreation. Timeless sex without procreation or a long time interval of sex without pregnancy ensuing seems quite improbable, given how probable it is Adam and Eve were created and maintained healthy and rather fertile (without disorders diminishing their fertility).