Actually, that's where the semen is supposed to flow, naturally. Into the vagina or birth canal.
I believe in natural family growth, that children are a blessing and all that, human population growth is beautiful because it allows more people to experience life, so if I was married, that would be the case, all the time.
Also, I think that the side effects of contraceptives are greatly underreported, and I don't believe in hindering the natural flow of human life. The most natural and elegant way, is the "no method" method of "family planning." No experimental contraceptives, no rhythm, no early withdrawal, but welcoming babies to happen whenever or as they happen. Sex is so much more erotic and natural, when pregnancy is a very real prospect, and babies are welcome to come along, if and as they can. To imagine we are doing our part, to help the huge human population grow all the more, makes sex all the more "sexy."
Of course it helps, that I am open to the prospect of having a possibly large family.