This is relevant because...?
Hypermnestra was pointing out that homosexuals are capable of love. If the argument is that love is a part of marriage then this would e relevant.
Both males and females are capable of love, so there is no reason a male with a female disposition or a female with a male disposition should not be able to be in love.
If you're going to be technical about it, love and lust are different emotions.
Since we want to get technical about it.
Romantic love, Dr Fisher explained in a lecture at the 2004 American Psychiatric Association’s annual meeting, is not an emotion. Rather, it’s "a motivation system, it’s a drive, it’s part of the reward system of the brain." It’s a need that compels the lover to seek a specific mating partner. Then the brain links this drive to all kinds of specific emotions depending on how the relationship is going. All the while, she went on to say, the prefrontal cortex is assembling data, putting information into patterns, making strategies, and monitoring the progress toward "life’s greatest prize."
Dr Fisher divides love into three categories involving different brain systems: 1) Lust (the craving for sexual gratification), driven by androgens and estrogens; 2) Attraction (or romantic or passionate love, characterized by euphoria when things are going well, terrible mood swings when they’re not, focused attention, obsessive thinking, and intense craving for the individual), driven by high dopamine and norepinephrine levels and low serotonin; and 3) Attachment (the sense of calm, peace, and stability one feels with a long-term partner) driven by the hormones oxytocin and vasopressin.
http://www.mcmanweb.com/love_lust.html
So basically love is just a driving mechanism with lust just being one part of it.