Charis

Only female humans had the “consequence” of “your desire will be for your husband”. Female animals only mate when fertile.

Animals (even monogamous ones) fulfill “be fruitful and multiply” WITHOUT “your desire will be for your husband”. They have a periodic appetite they feed which takes care of being fruitful and multiplying. You have noted that conception and birth would need to have been infrequent with immortals.

I don’t think there will be sex in heaven, yet people will be more satisfied. What if the intimacy in the Garden was intensely satisfying without lots of sex? What if sexual intimacy was infrequent before the Fall, just a periodic appetite as it is for animals?