If you’ve heard of NFP, you’ve probably heard about all of its wonderful effects. You’ve probably heard about how it gets you and your husband in tune with your body. How it teaches you both to be disciplined and how straightforward it can be. How it helps you focus on aspects of your relationship other than sex. How it makes things exciting and how every month you have another honeymoon. You’ve probably heard that NFP strengthens your marriage and makes you more fulfilled, more in love, and happier.

And though I appreciate those sentiments and have no doubt that NFP has improved countless marriages, I’ve always felt like the stuff I hear and read about NFP sounds a little bit like an infomercial. It sounds a little too good to be true. I await the sped up “side effects may include…”

But so often, the side effects of NFP are written in fine print below the many benefits. So I’m not surprised that many people don’t trust it and don’t give it a chance. We sense that there has to be a downside. And I’m going to tell you assuredly that there is. And what is it? It’s not that it isn’t effective. Abstaining when fertile is most certainly effective—it’s in the couple’s hands to decide how liberal they want to be about that abstinence. The problem isn’t about charting—charting isn’t that complex. Plenty of women chart their cycle for all sorts of reasons from hormonal imbalance diagnostics to preparation for conception. The problem with NFP is the abstinence.

Because the truth is, abstinence for the sake of postponing children, while perhaps prudent, is not some glorious thing. It’s self-denial, plain and simple, and self-denial hurts. It varies in its degree of hurt—for some lucky couples the abstinence is a couple of days a month. For some couples it could be weeks or even months at a time if you’ve got really crazy cycles. Either way, NFP means regularly depriving your marriage of sex—that expression which comes physically and emotionally most natural to romantic love.

And what does that do? That hurts you and that hurts your spouse. I’d say it might even hurt your marriage. Yes, NFP may hurt your marriage. That’s the fine print.

But in the end, it’s worth it. My husband and I still use NFP. But not for all the “benefits.” We use NFP to avoid doing what we consider to be wrong—we use NFP to avoid using contraception. The wrongness of contraception (something I’d like to address in the future,) is NFP’s true and only real selling point. We don’t practice NFP to “bring us closer together.” We don’t do it to “spice things up.” And we don’t do it in order for me to “get in touch with my body.” Really, we shouldn’t need NFP to do all of those things. The popular idea of needing NFP for marriage is contrary to the very philosophy of marriage. The philosophy of marriage says that though absence may make the heart grow fonder, it is better to grow fonder by choice, with presence—indeed, with prolonged, evolving, natural presence. The philosophy of marriage says you don’t need “monthly honeymoons.” You need one. And it’s not the end-all-be-all of your entire marriage. It is a step in a journey and adventure together. It is a step in a lifelong commitment to giving and receiving. Given that we believe contraception is a contradiction to that commitment, we have enough reason to practice NFP so we don’t deeply harm our marriage and ourselves in the times when we aren’t ready for children. We practice NFP because we find it better to suffer together than to sin together. And do we benefit despite the suffering? Of course we do—but not because of what NFP is. We benefit because of what NFP isn’t.