And if said foreplay does not lead to Procreation...?
Under what conditions?
At this point, we get into mind-reading. The Church is not an institution devoted to mind-reading, but rather the teaching of Moral Instruction.
Aside from Abortifacients which as always wrong, the core teaching seems to me to be, "Christian Couples should not be engaged in a Contra-Conception Morality". If a Marital Couple are enjoying some physical intimacy one night, and decide for whatever reason to NOT fully-consummate (maybe she has a "head-ache" for all I know), I don't see any possible "problem" with that.
On the other hand, if a Marital Couple are deliberately using "foreplay" to avoid procreation on a continuing basis, then we are outside of a pure question of "Christian Liberty" and into a question of "Contraceptive Mentality". I don't propose to read their minds, but I will point out that a contraceptive mentality is Immoral.