Dwelling over someone leads to disaster?

I'm writing this to get a more generalized opinion from the Advice Column over whether dwelling over someone will lead to screwing up a relationship.

I was wondering this earlier in the week because of what my friend did not too long ago. You see, whenever he hooked up with a girl he'd start to obsess about her. He'd always talk to me about what she was like or wonder what she was doing. It'd be like "Amy this...blah blah....Amy that" whenever we hung out.
Then earlier this year he started talking to another girl. Only this time his stance on the whole thing was to just "see what happens" and he never really mentioned her unless he was on the other line with her (if I called) or something. He's been with her for a few months now and it's definitely the best relationship he's been in.
According to him, his secret was being able to keep his cool with her because he wasn't constantly obsessing over her. Well that, and she's a nice girl which seems to help too.

Now I'm starting to wonder if I should practice this "go with the flow, and don't be like a creepy stalker" mantra with a girl. (bad way to word it, but you get the idea)
I remember the last girl I dated--before I moved in the summer--I royally goofed with because I couldn't be myself. I'd always go out of my way to try to be funny or way too accommodating, which she probably noticed and realized that I wasn't able to be in a serious relationship.
I dated another girl where I didn't constantly think about, and things went smoothly until she pissed me off. But at least that lasted a few months instead of a few dates. The thing with her is that I didn't "put the pussy on a pedestal" and I was A-OK when I was with her.

So I'm wondering what you guys think of this "go with the flow, time will know" kind of thing when it comes to a new girl/boy friend.

Does anyone have some personal experience with obsessing over someone to the point of screwing things up?

Jam it back in, in the dark.

Originally Posted by ElectricSheep

Which is why you need to accept the fact that you will face rejection, and you need to suck it up and move on. Not everyone is going to like you. How far do you think you can really get if you just stick your hands in your pockets and wait for someone else to make the first move for you?

Of course you'll face rejection. There are no perfect situations in life, and trying to ask a girl out is one of the stickiest situations a guy can get into. (no puns intended)
If you're not willing to throw hazard into the wind and just try your luck, you'll never get anywhere in the world.

There was a quote by Robert A. Heinlein, recently posted on a Quote of the Day thing I check every now and again, in which he said
"Of course the game is rigged. Don't let that stop you--if you don't play, you can't win."

How ya doing, buddy?