One of the things that people can do when they feel stuck is to look at how they '"frame" their thoughts.
For example: "We should have more 'life' in our marriage." Considered from other angles, it may be just as true to say: "We shouldn't have more 'life' in our marriage. It already contains plenty of life – our children and an agreeable relationship as we raise them." Or, "Our marriage shouldn't just be 'about the kids'" might be seen from this angle: "Traditionally and practically, most marriages become 'about the kids' while the children are young, and in more traditional societies, that is the main point of marriage."
My point isn't to convince you to stay in a marriage that isn't satisfying. I left a marriage that needed to be abandoned, and raised my 8yo daughter on my own until I eventually remarried. But if my husband and I had been on friendly terms, had been able to communicate, or had a more-or-less equal relationship, I probably would have stayed and it probably would have "worked" well enough to get our daughter raised. Financially and logistically, it would have been so much easier. And there was always the future possibility of splitting up once she was out on her own. But he was emotionally abusive to both of us, and the situation finally became untenable. Having any "life" or "romance" in our union was the least of my worries.
So, what I'm suggesting is that if you really can't see leaving the marriage as workable, or that it would create avoidable pain for your children, or even if you notice that dividing your household will probably cost a great deal more than you expect, you give yourselves some time to look at your marriage from other angles. Here's one that surprises a lot of busy young marrieds: A lack of romance can be a GOOD thing while the kids are toddlers. Their demands are so high (and your work lives are so full) that if you can get by without regular sex, that can be a boon. (Not every marriage can do this, because one partner's physical needs may remain high in spite of busyness – and then it's a serious problem.)
Have you thought about what your romantic life might look like if you were to divorce? It's awfully hard for a busy young mother to find a romantic partner who is willing to work around and include her kids. Happens, of course, but it's not guaranteed. So then you are just a busy single mom working and mothering more or less full time without even the relationship that contained companionship and sharing and good mutual parenting and a history.
And the last thing about romance is this: that first blush of passionate togetherness and connection changes. Even in the best marriages, it becomes something different and often surprising. The drive-you-wild edge blurs, you get to know what to expect from each other and the element of surprise and newness softens. At that point, couples may drift apart and go looking for "new" again, or they may accept the fading of intensity as simple reality, and not so bad at that. A committed relationship has much to offer, even if passion fades.
You are ultimately the only one who can determine what you truly need. I hope that as you do this, you'll also keep in mind what your children need. They came into your marriage at your behest, and there is real responsibility leaning on you because of that simple fact.
If you would like to explore the idea of reframing your thoughts, you can do this at no cost with a remarkable process called The Work, as taught by Byron Katie (http://www.thework.com/index.php). At the website, you can download some worksheets and follow the process to see whether it can give you freedom from the thoughts that are making your life seem less than agreeable. My husband and I, and a number of my acquaintances, find this process to be a source of surprising insight and happiness.
I wish the best to you and yours.