And as far as Natalia & Calleigh are concerned, I don't think Calleigh even deserves her friendship. If Calleigh had all these oh so wonderful thoughts about Eric then she should have been a good enough friend to at least get a feel from Nat how she would handle it. You don't do it behind someone's back & wait for them to find out thier little "secret" & THEN ask them. That's bullshit. I have no respect for Calleigh or Eric at this point.
Whether some think Eric/Natalia had closure or didn't (sorry I don't call an asshole husband dying CLOSURE)- it does not matter! Truth is TPTB actually wrote it, it did happen, & no one can try & tell me that it wouldn't be akward as hell carrying on a relationship with someone with thier "ex" right there in the lab with them.
I respect your opinion, but I have to disagree with some points you made. I don't think Natalia's ex-husband's death had anything to do with Eric and Natalia's relationship or the closure of it. Natalia and Eric had a fling (whether it could've been something more if the writers had played it out differently is up to the imagination, but it's certainly possible), and it was over by the end of Season 4, before Nick came back in the picture. Obviously, with the revelation that Natalia was the mole, and how Eric reacted to that dredged things back up, but I think we were to assume by the first few episodes of Season 5 that they'd patched things up and were friendly again (like that scene in 5.02 with the two of them in the garage). Yes, there was that scene when Nick came into the crime scene, and also the fight between Eric and Nick, but Eric has always been protective of women in general, and I don't think his reaction had anything to do with being romantically involved with Natalia at that point. He may have been more protective of Natalia because he knew what she'd gone through, and had at one point been in a relationship with her. But from what I saw, I believe the closure of Eric and Natalia's romantic relationship was at the beginning of Season 5. The stuff with Nick was a bump in their friendship and working relationship, but things seemed fine after that. They still work cases together, joke with each other, etc. It's not like they've been avoiding each other ever since.
I also understand what you're saying about Calleigh and how she should've kept Natalia in the loop about starting a relationship with Eric so that the friendship between the two women would not be compromised. It's entirely possible that they did "behind the scenes". The show is only an hour, they cannot show everything. The show is also a crime drama with hints of personal lives, not the other way around. I don't think it was important to show that on-camera. I doubt Natalia would even have a problem with it, given the fact that in the end of Season 5, Natalia witnessed Calleigh kiss Eric on the cheek (and didn't seem bothered by it when she asked "What was that all about?"), and then teased Eric about it in the next episode(also didn't appear to be bothered by it.) If she wasn't bothered then, I doubt she'd be bothered now.
And finally, like I said, Eric and Natalia's relationship was more of a fling, and it was quite a while ago. Plus, they are all ADULTS, not jealous teenagers stealing boyfriends. It doesn't
have to be awkward in the lab. Natalia could very well be aware and rooting for them. And a great deal of the Calleigh/Eric personal stuff is not shown, or if it is, they're not talking about it with everyone there. The scene between the two after Eric's therapist is murdered? Outside the entrance to the lab, not "romantic", and not many people around. The conversation by the mailbox while waiting for Tripp was just the two of them. Eric leaving her chocolates, then calling her? AFTER work. The "mushy" stuff said in the hospital? In the hospital, just the two of them, again. It appears that the upcoming kiss is nowhere near the lab or any of its employees. It's not like Calleigh and Eric are going to go around making out all over the lab. Even in the last episode, they had plenty of scenes together, but all of them were completely professional.