I highly suggest you look into Gottman's books on marriage. I found this blog and it looks like it has some of the exercises that are in some of his books. http://www.gottmanblog.com/ Gottman suggests that you don't need to be crazy in love ... you just need to be appreciate friends. For me, this approach works.
Relationships are hard especially with little children in the picture. I know SO MANY people that just fold on their marriage right when their children turn 3 or 4.
You have a child. You are talking about meeting and loving other men, probably introducing them to your daughter at some point. Not to be a jerk, but how do you feel about another woman being a mom to your child? Because if you are meeting other people, your partner will be too. And men usually remarry quickly after divorce, which means there will be another woman in your child's life. This may not seem like a big deal but it can be.
I remember many years ago a man who had been married 25+ years telling me that everyone at somepoint in a marriage is tempted and thinks they may have made a mistake. Maybe they meet someone who seems really great and they can't help wonder if there relationship would be better with this person rather than the person they marry. Character is sticking with commitments you make.
I recommend doing everything you can to save your marriage. Divorce shouldn't be the immediate go to. Work on your marriage. It will shape your daughter more than you think. All the best.