1)  A commercial cake-baker or cake-decorator is not "celebrating" anything when baking or decorating a cake.  The person is doing a job to earn a living.  The person often does not even know the people for whom the cake is being prepared, let alone participate in any of the festivities.
2)  Reducing a marriage to sex tells more about the one who is doing the than about any married person -- and yes -- same-sex marriages ARE marriages under the law.  Your observations to the contrary are sadly reminiscent of comments made by those who opposed interracial marriages.