On that note, I will offer some real, practical advice: the 90-day rule.
This one came from a buddy who, after a messed up divorce from a woman he married too young when he lived abroad and was homesick, was single from about the age of 25 or so until 38 when he married the right one. He dated a LOT of women over that stretch, to the point that he developed what he calls the 90-day rule.
If you've been dating 90 days and you don't see a real, legitimate future with her, to the point where you actually think she's "marriage material", break it off at 90 days.
That's not to say that every girl that makes it past 90 days is a soul mate, but if you can definitively say that it's a no-go at 90 days, it's not going to get better. Doesn't matter if there are positive things about her. Doesn't matter if the sex is mind-blowing. Doesn't matter if she's ridiculously hot and looks great on your arm. If you get to 90 days and you know she's not the one, don't waste her [or your] time. Taking a woman who you believe isn't right at 90 days and continuing it on risks you getting stuck with her because eventually both of you get so entwined that neither wants to break it off but neither really wants it to continue, and that's a recipe for unhappiness down the road. Rip the bandaid off at 90 days and move on instead.