Alright, since I've already enjoyed the amusing visual gag in today's strip, it's time for some over-analysis.
The issue of readers having unrealistic expectations of perfection has been brought up a couple of times in the past week. That's not why there are objections to the way certain characters are handling their business. When we consume fiction and react to fictional characters, we're (generally) not holding them to an unrealistic standard of perfection, but we do compare them to the real world, particularly when the characters are well-rounded, realistic, and relateable.
To that end, we don't ask them to be perfect, but we do ask: are their actions, attitudes, and motives understandable? Reasonable? Sympathetic? That's what shapes our reactions to the characters and their role in the plot.
Take Marten here. What he did wasn't the best thing he could've done, but when we examine his reasons, they're understandable. He's in a difficult situation, so it's reasonable that he doesn't want to unpleasant issues from the past or get tangled up in someone else's argument...particularly as it involves his boss and his ex. Tai has, directly or indirectly, asked a lot of him: being cool with the way she lusted after Dora while she and Marten were together, not making an issue out of her wanting to make a move on Dora almost immediately after the break-up, and waking him up in the middle of the night to seek reassurance and support after her first date with Dora. One can sympathise with Marten's position, even if you don't completely agree with his handling of the situation.
Compare that to last week's "bad friend" moment with Hanners and Marigold. It's understandable that Marigold isn't that interested in the proceedings, callous as that may be, but ignoring Hanners was not a reasonable way to treat a close friend and guest. Her lack of common courtesy and support for a friend who has been very kind and supportive to her makes her unsympathetic; instead, Hanners is the one most readers would sympathise (or even empathise) with. It's not that Marigold is imperfect, it's that in this particular situation, her actions don't pass the understandable/reasonable/sympathetic test. At the very least, they score lower than Marten's actions do.
Of course, in both cases, it makes for a funny punchline. Amusement and criticism of the character's actions (or reactions) are not mutually exclusive. We can roll our eyes at Marigold's lack of social grace, while also chuckling at her butchering of the details. We can sympathise with Marten's situation and laugh at the "NOPE" reactions, while also acknowledging that it wasn't his best move.