Well, completely ignoring the Smallville part, because I think the show runners of that series made it pretty clear that Lana was not Clark's true love, there's a lot wrong with the rest of what you said here.
Firstly, DC is a business. They are in the business of selling comics, which tends to require them to not alienate their fanbase. So, yes, they should absolutely take fans' opinions and wants into consideration. That's not them "caving" or "giving in" or whatever. That's them actually listening to their fans and actually giving them what they want. That's what a business like DC is supposed to do.
Secondly, again, its not a matter of fans being impatient. Its a matter of them not wanting to rehash developments that already took place long ago. Again, we saw the Clark/Lois relationship unfold and culminate in marriage...twenty years ago. Not wanting to rehash something that we all read is not being "impatient," that's simply a want to move forward as opposed to moving backward in terms of character development. Lois and Clark are married and have been married for a long time. We don't need to rehash the telling of their romance again simply because some weren't around the first time they got married. I was 5 when they got married the first time, and read the story of their courtship and marriage much later on. People are able to catch up, even if they weren't there.
And lastly, did you even read their relationship first time around? Because they already went through all of what you're asking for. The got together, got engaged, he died, she grieved, he came back, they experienced problems, drifted apart, she went away, they got engaged again, and then ultimately got married. So, in short, they've done that dance before of drifting apart and coming back together out of their love for one another. We don't need to rehash it. All we need to do is move forward with their marriage.
Uh, yeah, I did read it, actually. You do know that the memories that Wally has brought back with him aren't the actual Titans continuity that Wolfman, Perez, and Grummet spent many years crafting, right? Instead, its that Frankensteined, Titans Hunt continuity that Abnett and editorial cooked up. He might remember NTT, but the rest of them do not. Now, I hope that when Wally sees Kory, Raven, and Vic again, he'll somehow re-instil in them the memory of them being together on the Titans, but it might require a change of the editorial guard. For now, they do not remember their most famous adventures together (aka the Wolfman New Teen Titans run), which sort of puts their "real Titans" status into question.You haven't been reading it, have you? They all do remember it all. Electrostatic transmission of memory at Wally's touch. He hasn't given Kory and the rest that touch, but I expect that's only because Editorial doesn't want to break up the current sidekick club.