What's the harm if James didn't get the message? Only just before the phone call happens, Marina talks about how 'they' ("we", I assume Marina and her two cousins) found out Nikos' house was bugged and the driver disappeared in thin air (page 471).
I don't see how a guy who can't handle 'no' for an answer is anywhere on her priority list at that moment if everything that happens is to be taken at face value. Marina wasn't intimidated, nor does she feel the need to put the bald stalker in his place. Why does she feel the need to do anything but ignore James?
Because James is the one going around openly calling himself her Husband. If you take everything at face value, there's a number of reasons why this would be upsetting for Marina.
1) If her family is in danger/under surveillance, she might not want to endanger the life of someone that's uninvolved.
2) She doesn't want Andrew to hear and think that she's been unfaithful.
3) She doesn't want the rest of her family to hear and again, invite questions of infidelity. One of the things we're told by Niko's daughters is that (supposedly) Marina values loyalty above all else. That was the justification for apparently them all insisting that Andrew honor the promise he doesn't remember making.
Also, how does James know which exact hotel in Athens Marina is staying in? What are the odds he doesn't know and just randomly finds her hotel?
See, I took that to be why she was so upset/surprised that James was in Athens; that she didn't tell him where she was staying, and he showed up and found her anyway (which would be offputting as hell). Honestly though, even if she did mention which hotel she's staying at, the fact that she's surprised he's here tells me that she didn't invite him to continue a fling. Seems more likely that the hotel information came up in casual conversation. ("I'm a journalist visiting family in Athens. What does my family do? Oh, my Uncle owns the BlaBla hotel...")
I think it's more likely more happened in Crete between James and Marina. She clearly doesn't want to talk about exactly transpired in Crete on page 442. If it was just some random fella pretending to be her man, why would she duck that question like she does?
I mean, she also doesn't mention being threatened with a gun (page 1117). You could argue she didn't mention James for the same reason she didn't mention the gun. Or, the same reason why a husband will say he's meeting an old college friend "Sam", and doesn't bother explaining that Sam is short for Samantha. Even if nothing happened or will happen, if you consider the situation "closed", you might not want to have to explain and defend yourself over a "non-issue". Especially if we're all saying that their relationship is in a rough patch.
This would follow if we prescribe to the "Nikos is evil" theory. I've been going back and forth on that, but currently I don't think he's evil.
I don't really know/care if it goes either direction other than whether it makes sense once we see the full picture. Right now, Nikos being a passive participant doesn't ring true to me. We've got very little characterization for him personality wise, but from a behavior stand point the one thing we have seen is that he seems awfully eager to be making out and fucking his niece's husband once femmed. That seems a bit beyond "lonely rich guy is eager to reconnect with someone and when the opportunity comes will leap on it" and more towards "seems like this guy wants something and seems willing to take things down his preferred direction." Going back to Page 68, him getting on one knee and proposing always felt weird to me. It wasn't done playfully, it was something Nikos intent on doing. Same with him making out with his niece's former husband in front of her. There's keeping up appearances, but then there's making a show of it. And often, his actions seem to lean on the later, in my interpretation.