In terms of its relation to marriage you can do one of two things with reproductive technology. You could say, only married people can use it, on the grounds that you should not be affirmatively at law encouraging people to have babies out of wedlock.

Or you could instead analogize to unwed childbearing and say, gee, if we are going to permit so many single parents to have babies as a result of sexual passion, why should we ban thoughtful single parents from reproducing using technology?

But neither line of argument threatens the core case for marriage.