The following is taken from a declaration on sexual ethics published by the Vatican Congregation for the Doctrine of the Faith. It was issued in January of this year and is considered church doctrine by Catholics.
On Premarital Sex and Marriage
“Experience teaches us that love must find its safeguard in the stability of marriage if sexual intercourse is truly to respond to the requirements of its own finality and to those of human dignity. Those requirements call for a conjugal contract sanctioned and guaranteed by society.”
Homosexuality
“In sacred Scripture (homosexuals) are condemned as a serious depravity and even presented as the sad consequence of rejecting God….(H)omosexual acts are intrinsically disordered and can in no way be approved of.”
Masturbation
“…The faithful have declared without hesitation that masturbation is an intrinsically and seriously disordered act…(T)he tradition of the Church has rightly understood it to be condemned in the New Testament when the latter speaks of ‘impurity,’ ‘unchasteness’ and other vices contrary to chastity and continence.”