First of all, GOD BLESS YOU for participating in RCIA! I myself am a recent convert and can assure you that it has been the most amazing experience of my life. I’m excited for you!
I think what the priest was trying to get at was probably the idea that sex isn’t something we’re all “entitled” to just because we’ve reached puberty, and even within marriage, we need to leave the act open to life (in that we don’t CLOSE it to life by artificial means), and it should occur with respect for its true meaning (not taking place out of pure selfish lust).
Speaking as a college student, so many people really do think of sex as just a recreational activity. And many couples, after marrying, shout the mantra “We’re married! What goes on in our bedroom is our business!” But the previous poster has got it…it’s a complete and total giving of self, which, I would add, takes place as part of your Sacramental vows before God. So of course God and morality has a place even there…ESPECIALLY there, since it’s twofold unitive and procreative purposes are supposed to be a reflection of Christ’s Love for the Church.
So, bottom line, I’d be willing to bet that that’s what the priest meant. There are many threads on this forum (some just general threads, others answered by the resident apologists) that affirm that a married couple who is past their childbearing years (or infertile for any other natural and uncontrollable reason) may certainly still engage in the marital embrace. The moral issues come in when someone is purposely frustrating the very nature of spousal sexuality by bringing artificial contraception into the picture (or when lust becomes an issue because one spouse is viewing the other as nothing but a means to satisfy their urges and is losing focus of the true meaning and beauty of the act).
God bless, and stay strong on your journey
