I agree with the fact of saying that in the heaven there will no marital act. But, i disagree with the explanation, sex is a procreative act. That is too simple, it is very reductive, like motives. In reality, that is more complicated.
In addition, I want to say that in the heaven, we will be body and soul (glorious body via the resurrection and immortal soul). We will be almost as angel, but not like them, with our own sexed glorious body.
WE ARE NOT ANGELS. WE ARE HUMAN BEINGS, WITH A SEXED BODY, AND A SEXED SOUL, AND EVEN IN THE HEAVEN.
NOT MARITAL ACT IN THE HEAVEN.