Does Engels and Newton Work?

While Engels does point out that sex roles come out of monogamy, but does not go into the complexity that newton does when she explores gender. Engels critique of monogamy and sex love may work for heterosexual couples, but not for homosexual couples, since they are not monogamous for procreative reasons. Therefore, Engels argument should be amended in that heterosexual couples of the lower class and also homosexual couples are able to enjoy real sex love because they are monogamous for reasons other than the desire to pass on their private property.