What's his fortress like? Where's it located? I actually used to subscribe to that book (Lois and Clark), but it was honestly (And I am not just saying this to knock Superdad) pretty forgettable. I just kind of remember it like, um, Clark and Lois raise Jon in California while Clark secretly stops monsoons and stuff and Lois writes books. Once they visited Metropolis for a brief vacation and almost ran into Jimmy Olson, that was pretty exciting. Even the intergang stuff and Henshaw didn't really do it for me. And I cancelled the subscription, so if the fortress was introduced recently, I'd have no way of knowing about it all (Don't have the most recent issue or two, probably).
I remember as I was reading the early issues going "Man, these are boring, let's get Clark interacting with the new universe versions of the his old friends from Metropolis and the Justice League.". Classic example of "Be careful what you wish for, you just might get it.". I'm glad I didn't say that to the editor or something, or I'd really be kicking myself. Obviously, I just meant as a side character in his own book, though, not replacing Superman as Superman.
Yeah, I'm not just Superman going "Well, Diana, I wanted to tell you, but the Superman/Wonder Woman comic title wasn't scheduled for an issue until this week." is going to fly as a good explanation for his girlfriend within the fictional storyline. He might have had an excuse if he had only told Batman, and gone for a better diagnosis and an evaluation of whether or not a cure was possible, saying he wanted to be able to get a handle on the situation and know what to tell Diana before he told her, but the problem is, he opened the first book of this arc with "I'm dying", told Batman he didn't want a second opinion on the diagnosis, told Batman not to look for a cure, and seemed to have plenty of time between asking Batman to look for Kara and Batman telling him he found her to try to track down Wonder Woman. And, you know, it's not as if Wonder Woman would have been a hindrance to tracking down and "rescuing" (in quotes, because in the end, it turns out no rescue was required) Supergirl- Wonder Woman is her own superhero, and she's always agreed that they both need to put the world before their relationship, she could have assisted him just like Batman (Well, more in the fighting than the computer research), and probably would have.
The only reason that makes sense as a good excuse would be if Superman and Wonder Woman are broken up. You don't really have an obligation to track down your *ex*-girlfriend to tell her about your new incurable non-contagious medical condition before you tell anyone else. Your girlfriend, you probably do. It's not like you have the ability to almost instantaneously fly anywhere in the world to have a conversation- oh wait, you do, you're Superman.
Of course, that Clark doesn't really have a good excuse for not telling her if they're still dating isn't necessarily a continuity error for the storyteller. Maybe he's just writing Clark to act like an ass or have some sort of emotional problem with telling the woman he loves that he's dying. I mean, the guy is human- er, Kryptonian. Whatever. He's not perfect. He does some of the same type of things bad romantic partners of both sexes do to each other all the time. He's got the same potential imperfections with interpersonal relationships as anyone does.
But, within the story, if I were Wonder Woman, sure, I'd be pissed. I'm a guy, so I'm not into imagining myself as Wonder Woman, but you know, if I were dating a woman who was acting like Clark...
Which reminds me, he told *Lana* before his girlfriend. That's really what's going to hurt him with Diana, I'd imagine. Like, okay, Bruce is trying to help you find your missing cousin, Kara is your cousin who you want to carry on your legacy (Interesting point there- Clark could in theory try to explicitly pass the baton to Supergirl, his flesh and blood from his own universe, and not to SuperDad. I doubt editorial will allow it in the end because of how they are handling Rebirth, but it'd be a better story. Not only could SuperDad sort of be a fake in the eyes of the Justice League and the Daily Planet Clark Kent friends, but what if he's actually usurping duties and legacies that Clark Kent explicitly tried to leave to his cousin? The Justice League and Lois and such could be really pissed.), but there's no reason he had to actually find Lana and tell her before finding Diana and telling her. I guess Diana could have been busy battling Titans or whatever she does in her books, but from her approach at the end of AC #51, I get the feeling she wasn't.