Smallville made much more of the Lana character than was comic canon (or movie canon for that matter). It developed the relationship bewteen Lana and Clark into both a sexual one and Lana as the forever love of Clark's life.
Although Lana's character has disappeared from the Smallville screen (the actress's didn't wnat to renew her contract), there has been no contradiction of that story line. As far as the viewer knows, Lana still is the love of Clark's life, and Lois is, well, whatever, handy I guess, with Lana's absence. So although there is now a change in the physical relationship between Lois and Clark, it's not a relationship to be taken seriously on his part.
The other thing , too, for me anyway, is the character changes that Bobbart mentioned. The series has changed Clark Kent's personality as well as Lois Lane's, and also really never took the character of Lois Lane especially seriously until this season, and perhaps some of last. At any rate, for me, when the primary personality traits of key characters have been changed it's as difficult to buy into the show as if they had decided to physically alter the characters -say, for example, Clark Kent was short, had red hair and freckles.
btw, I'm betting, that the Smallville writers will bring Lana back in a "guest appearance" cliffhanger, that makes it pretty clear that Smallville Clark Kent is still and will always be love-of-life smitten with Lana.
carol
