TMI alert. Please don't read further if you know you don't want to know about these things.
Anyway, for any erotic inspirational romance authors out there, here are some gems that may help you guys out in those oral sex scenes in your books:
Is the sexual act in question Free, Total, Faithful, and Fruitful? Is oral sex open to life? Can life come from oral sex? Is the Holy Spirit able to create life from oral sex?
Answer: No. Oral sex is not allowed in a Catholic marriage.
Oral sex between a husband and wife is morally permissible as long as it is mutually consented and as long as the man's ejaculation is vaginal. Before or after intercourse does not matter.
The husband can bring his wife to orgasm with no problem. If the wife performs oral sex then she needs to not bring her husband to ejaculation.
Bottomline: oral sex is morally permissible between mutually consenting husband and wife as a form of foreplay or afterplay as long as the man ejaculates vaginally.
Oral sex is contrary to natural law (even as foreplay) and here is why:
Thus, with regard to the human person, the Creator has designed the digestive system for nourishing the person, speech for communicating the truth, the mouth to swallow food for nourishment etc. Likewise, the Creator has designed the sexual organs for something, namely, for procreating children and for expressing the personal communion of the spouses.
However, an action of the sexual faculties outside of the marital act would be lacking in any procreative dimension and consequently in any unitive dimension; it would be "sexual pleasure...sought for itself, isolated from its procreative and unitive purposes" (Catechism of the Catholic Church, 2351), i.e. lust. Therefore, this kind of sexual action in question cannot be justified by saying that it leads to the marital act; it is by nature a separate action whose object is gravely immoral.
All those who are stating that as long as there is marital intercourse that oral sex is OK should tell couples of the physical risks, and the spiritual risks to their marriage.