This quotation from the second creation myth at the beginning of Genesis is not particularly relevant to the issue of LGBT rights, or even to the marriage of same-sex couples. Its context in the Synoptic gospels, as the character called Jesus applies it, has to do with whether divorce can be condoned, according to Jesus's special insight into the will of God: "What God has joined, let no man put asunder." (We note that even Matthew quibbled with the absoluteness of the statement in Mark.) It has nothing to do with which individuals may be married in the first place.

It's likely that the historical Jesus may have thought as little of same-sex relationships as did his Jewish contemporaries. But we don't know that, and he surprises us with other counter-cultural innovations. Anyway the gospels have nothing on the subject. 

Children should certainly be considered instances of God's blessing. But their presence or absence should not be used as a sign of whether God favors a sexual union.