Political.

Great answer! There would be a lot of ways to develop an analysis along political lines.

If I were writing it I would key off of the emphasis on "heterosexual" in the caption. I might compare the image of the couple with some image like this:

Then I might talk about how the notion of "legitimate affection" is politicized because of homophobia and heterosexism. I would define those terms and then discuss how images of heterosexual couples dominate the media because of discrimination. People in ad agencies can act as gatekeepers, enforcing institutional discrimination. I would talk about how genuine love is possible between ALL couples.