Well, there's always the obvious option as well - this doesn't have to be a romantic thing. Or even a casual fling. She and Jim just got into an apparently successful deal together. His plan might be to discuss business, or simply to celebrate how well it went for them.
Of course I'll grant that it probably is an attempt at romance on Jim's behalf. But then, there's no reason why Dora shouldn't accept anyway. He's apparently successful, and Raven at least thinks he's good-looking, even if he apparently isn't fond of his ex(es). Accepting an offer of dinner doesn't mean she's going to become his new wife, it doesn't even mean she has to sleep with the guy. They can go out, and if it fizzles, they don't have to go out again. At the very worst Dora might have to endure a few awkward moments in exchange for dinner.
If they do sleep together... well, Dora clearly doesn't attach the same significance to sex as Faye does, though it's clearly important to her. Now, if Jim gets Dora drunk and knocks her up, that might be a disaster, but since last time I checked QC wasn't a soap opera I don't see that happening. It might be something of a relapse for her if she ends up sleeping with a guy who's not good for her, like the Alpha-Dicks she used to date, and that would suck... but I think even then her therapist could offer some advice. At least she'd be opening up a little after The Big Breakup.
And hey, let's assume that this date actually leads to some kind of connection and Dora does end up dating Jim for a while. Which means that, well, she's dating someone. And... unless he's abusive, I don't see the downside to this. If she likes him enough to do it, isn't that a good thing?
Basically, this date might make her little circle of friends a little awkward for a little while, but really, at the moment it already is. Where's the harm?