This is a season in your life - this is not forever. Having now been with my husband for almost 20 years, married for 15+, I can say that yes - we did go through those times There are days now with teens and ailing elderly parents where we still have those days. BUT (and this is a big but) having been through tough times - times without reward - we have a relationship has a depth and sweetness I would not trade. When your kids are little and they take every single moment of your waking hours, and you feel physically and emotionally drained it seems like such a desperate time in your life. But if the two of you can see this as a journey and can realize that this time is not forever, and can be mature and motor through the dull times and the tough times, and can manage to stay together it will be such a good good thing.
You really have to find times to go on walks, put the little one in a stroller at this naptime and take a walk together. Romantic times will be different than they were - but still wonderful. Find someone to trade babysitting with if you can't afford it, or use aunts, grandparents, etc. You don't need to go out to dinner or a movie - even a drive, a walk in the park. Now that Spring is almost here take the little one to a large park with open fields and let him run while you and your man walk holding hands. Take a drive at your little one's bedtime and when he falls asleep go parking. He'll be sleeping in the back seat and you two can make-out in the front seat. There are a lot of ways to sneak in sweet times together.
When my kdis were pre-schoolers and even in elementary school there were probably about 4 or 5 times that our marriage seemed destined to fail - because we didn't take care of eachother. I was certain he'd leave - he was being selfish, I was being selfish - we were fighting for "oxygen" - for our own needs and couldn't see how to care for eachother. Then 2 years ago a series of calamities began: the death of my FIL after a brief illness, my MIL having to go to a nursing home, the sale of his childhood home, my husband having an almost deadly auto accident (1 year ago yesterday), my mom's diagnosis of recurrent ovarian cancer, and many more things I can't even list. We found that we both had this reservoir of compassion for eachother, we took care of eachother's parents, we drove our kids to emergeny rooms, I sat by bedside of his dying father, he sets up the handicapped ramp for my mom, I soothe his mom's tears, and I held my husbands hand as he was wheeled in for spinal surgery near the base of his skull (he recovered wonderfully and is back at work as a sergeant with the NYPD). But before that time we only cared about ourselves. WE found that it's contagious - when I care about him and his needs, he in turn cares about me and my needs.
LIfe is made up of a daily routine of laundry, childcare, cleaning and work - but is punctuated by precious things like holding hands on a park bench, taking a walk together, laughing at stupid stuff, gazing at your beautiful sleeping child. It's also punctuated with tough stuff - particularly as you get older. But having someone by your side who will be with you through it all is precious. The 5 - 8 year time is tough - especially with little ones. But the rewards of sticking together are huge and so satisfying.