I think we have to "go there," as the Church recognizes the differences of "sex" between male and female and between a same-sex couple.  Indeed, that is the elephant in the room that Father Martin is either ignoring or acknowledges is there but is trying to sweep under the carpet, to extend the analogy.

Love is an act of selflessness, commanded by Christ for us to exercise toward everyone.  To engage in sex is an act of lust.  Surely Christ did not ever mean that to love one another ever means to anally penetrate them, did He?