Run2b,
I very rarely chime in on letsrun, but I felt as if your post warranted a response.
First, answers to your questions:
1) Relationship issues are serious, and they should be hashed out, as reasonably as possible, with both parties involved. But. You shouldn't beat things to death. So I look to the second part of #1 for more evidence, and from that I gather your relationship with this woman seems to have more good about it than bad. The answer, then, is that you might be trying too hard to grind this out. You said it yourself: She's cool and fun and you get along well.
2) No, there's nothing wrong with you. You seem to have your head screwed on mostly straight. A good thing. Again, I see "The girl is great..." in number 2, and that's another check for the both of you in the plus column.
3) You can never be an asshole for being truthful and honest. If you are being those things here, then you aren't an asshole.
Now the important part, the part that really sticks out: "But something is missing."
I know what you mean, and, since you have obviously had experience with other women, so do you. You've said you were with a woman you felt more in sync with. If so, then you should have a good idea what you want and what you don't want.
Which leaves me with this: You *must* find out, for yourself and for her, *what*, exactly, is missing. Ask yourself that question. And then answer it. And don't bullshit. If you can't do that, then you are probably f***ing this up, or at the very least making an iffy decision. Ask yourself tough questions. Then answer them. That's the way forward in a relationship. 'I don't know' isn't going to get you far in this situation, even though it's probably the easiest way out.
Relationships require effort. They require sacrifice. There are no perfect people, and there are no perfect relationships. You know these things. Which brings us back to the same question you must ask of yourself, and answer: What do I need that I think I'm not getting with this woman?
Kudos to you if you search yourself and honestly decide she isn't for you. But we're talking about emotions here, and we're also talking about odds. The odds of you continually finding a "match" are miniscule. Most people don't even get one chance at a good relationship, let alone multiple chances.
So I'm saying move on if you must, but if you choose that route, do so with complete confidence and a clear conscience.
Because when it comes to decisions, mixed emotions and nagging uncertainty signal you might be screwing the pooch.