Marten was mostly pissed about the ONS because she didn't remember his name (First signal of "you are meaningless to me"), and she really, super duper wants a boyfriend. Just not Mark. Or whatever your name is. (Slam dunk of "you are meaningless to me").
Nobody likes being defined as meaningless, even when they have no real reason to have meaning to someone else (Half of all internet arguments boil to "I'm not meaningless, you are!" The other half boil to Hitler). For the most part Marten seems to have handled it quite well. There was moping, but he quickly realized he was overreacting to the whole thing.
I don't think Delilah represents any kind of unfinished business for Marten. If he does for her, I'm going to be seriously disappointed in Jeph.
Why? I like writing women more that men, so I can understanf why QC's Cast skews fem. Every woman is not "crazy." The regular QC cast is largely neurotic girls, chill/mopey dudes, and Tai. (Tai is the sanest regular so far, but I suspect Veronica to take that position if she features more). I don't think this preponderance of "crazy chicks" is either a bias or a political statement. "Crazy" characters tend to be more interesting characters. But it's not because crazy, it's because unusual. There are more girls, therefore more "unusual" girls. Thus Tai. Her powere seems to have evolved into "Unusually sane." She's super intense about the feels, but also extremely reasonable. Dora could totes break her heart, and Tai would be okay, I think. Dealing is what she does, and how she became Marten's mentor.
Delilah (and Padma, for that matter) don't have any crazy, that we are aware of. Delilah just passed through. She judged Marten good enough for now, but otherwise not her type. Padma was terrified because she ran into a life-changing-level attraction in the middle of a life change. The situation seemed mutually exclusive. She didn't handle it the best of ways, but it was a pretty sane way to deal with it.
For either to show up with a burning torch for Marten would be a little nuts. (Padma would make more sense than Delilah, which is why I would not be a disappoint if that happened.)
Overall, if the ship is danger, I suspect danger from within. In today's (tomorrow's? I give up) comic is going to be painful, I expect a pun, or Jeph has thought up a whole new way to kick Faye while she's down, or Jimbo destroys Clinton's robot hand while declaring, "No! I am your father. Search your feelings. You know it to be true."