I am a Catholic convert. I have been for three years come the end of this month. Though I respect the Catholic church as both a spiritual and intellectual beacon and thus see it as a sign of hope, I have for some time now have questioned its teachings on sexuality. My biggest conundrums have been over contraception and masturbation, because a lot of times, they just don't seem to make sense.
But I understand why they cling to these teachings and though questionable, I know they are not without good reason. The Church is afraid of being reformed, especially in regards to its sexual teachings, because there is the mentality that if one goes, they all go.
Case in point (and this often cited by Catholics, especially conservative ones) on contraception, that it has been noted that many Christian churches, in particular the Anglican church condemned the practice of married couples using contraception prior to the 1930s. Following the 1930s, the Anglican church approved of this practice and many other churches followed suit. The Catholic Church, naturally, did not. So, there is an anxiety about reforming these sexual teachings, that if the Church lets one go, then an entire landslide of teachings are just going to fall away.