[Lush]

So basically, did some find the sudden enamouredness between Faramir and Eowyn as not particularly credible?

Yes and no.

maybe the more spontaneous relationships have more passion and will prove more unpredictable and interesting? What do you guys think?

Well, actually, my dear, "spontanous" relationships usually only succeed in tinging your hangover with regret and nothing more. [img]smilies/wink.gif[/img] But I digress.

Faramir had fallen in love, and Eowyn no better than an icicle.
When she finally did understand that her crush on Aragorn was just that- a crush, she woke to the realization the Faramir had tended her a loved her, and that she should decide as woman, not as a child. She overcame her girlish tendencies and became an adult.

You know, today it struck me that women chase after unavailable men are usually the same women that reject the men who offer them unconditional love and support. Hence Eowyn's behaviour is a bit incredible to me.
Then again, Tolkien was no psychologist, so I don't really hold it against him.
The only way I can rationalize Eowyn is to say that in Aragorn she saw someone who could elevate her status, thus falling in love not with the man, but with the image of a King (so basically, she didn't fall in love at all, neither did she have your typical crush), while in Faramir she found someone who had actually "awakened" her as a woman, not a leader or warrior, just a female.
Ultimately, I'm not really sure if this is realistic or not (or if bombur's ultra feminist friends will not give themselves nosebleeds over this), but it ties up that particular part of the story with a nice bow, and, like Tirned point out, leaves us with a sense of hope, so why not?