How did you make it through? or did you?

Myself [31M] and my wife [31F] have been together for 12 years and married for 9. We met and fell in love young, married young, and had kids young (we have a 7 and 9 year old). In our early relationship, we were both sexual, had almost everything in common, we hardly ever fought, and could talk to each other days on end. However, the last 6 years have been rocky. No infidelity or anything like that, but we lost a lot of chemistry. We don't have that much in common anymore, we grew to be different people than we were at 19. Sex drive has decreased with her drastically. We can hardly talk to each other anymore. If we try and have a serious conversation, it normally leads to an argument or one of us getting mad, someone taking something the wrong way, its like we don't even know how to communicate anymore. We try to get alone time and go on dates but we usually just end up going to dinner and talking about the kids or something. We still love and respect each other but i just don't think the spark is there. She isn't my "baby" anymore and I'm not her "soul mate" anymore. If we didn't have kids, I seriously don't think we would have stayed together. I know the old saying "marriage is work! It takes both sides and a lot of work!" but that's the thing, IDK if either of us really want to work that hard for it. I want to work for it! but at the same time I just don't know if the drive is there. We have in fact told each other what we need from each other to get our love back but even if we try and do it, its never enough.

I feel super guilty for saying this but I look at a lot of out female friends with more of a smile and more excitement than my own wife. I sometimes fantasize about other women and wonder what stuff they do for their husbands or what it would be like to be with them. I understand the grass is not always greener and this is an unfair comparison toward my wife. I just feel lost and don't know what to do. I do know that I don't want to feel this way though.

How do we get back to what we were? or are we just grown too far apart?