The conversation between Beth and Josh is wonderfully stilted and frustrating. They are both struggling to "say" what they mean without actually saying it. And Josh is already starting to feel Beth pull away from him... that little almost-flinch is so telling.
I remember watching that horribly painful little scene on the show where Josh said "We make a good team" and Beth gave him that fake smile. And it was so obvious, from the expression on her face as she lay in the dark with Josh's arm around her, that she wanted to be elsewhere...
I feel for both of them. But I agree that the relationship had already gotten a little stale, even before Beth met (or met again) Mick at the fountain. They just weren't meant to be. And I can't help wishing that they'd broken up so that Josh might have had a chance to live through the Tejada case. 
I was hoping that Beth's mind-state would come across that way....she's had an incredible day and been on an emotional roller coaster....she's still on a bit of an adrenaline high and the questions just keep coming. By the time she gets home, she's crashed, physically and emotionally only to encounter Josh laying in wait. The subsequent conversation is exactly as you describe - they need to talk, but under the circumstances where they're both exhausted and worried, everything just comes out wrong.
