Scientists say that the “honeymoon phase” in most relationships ends around the three-year mark. Couples stop dressing up for each other; date night becomes sitting on the couch; and make-out sessions turn into a peck on the cheek before you turn out the light. 

When 2,000 couples were polled, 67-percent said around the three-year mark in their relationship, stress peaked, and minor irritations, like weight gain or snoring, snowballed into larger problems. And compliments dropped from three a week – to ONE. 
So why is the three-year-mark so dangerous for couples? A big factor is HORMONES! About three-years into a relationship, production of the bonding hormone oxytocin drops. It’s called the “cuddle hormone” because it’s released during childbirth, nursing - and even those make-out sessions you used to have. That’s why a lot of manufacturers have come up with what they say is a new fix: An oxytocin nasal spray. It’s designed to boost levels of oxytocin, which studies show can keep couples feeling closer and happier. 
One study found that couples who sniffed oxytocin before discussing a touchy subject were less likely to argue. Manufacturers claim the over-the-counter oxytocin inhalers can improve relationships between partners, and increase attraction among strangers. But do romance-boosting nasal sprays really work? Well, right now, there are zero studies that show oxytocin improves relationships long term. 
If you want to boost your oxytocin, there’s no need to waste your money on sprays. Numerous studies show that hugging your partner for just 20 seconds triggers the release of oxytocin. And neurologists say, if couples made an active effort to be more intimate and touch each other more often, they could easily boost their oxytocin levels without the need for a drug.