I feel kind of bad saying this, but my mind did go almost immediately to those possible good reasons. Not even anything dramatic, just, does he not really support her much? Or does she just fairly often find herself supporting/reassuring him without getting much back? Because I could imagine a person going through some kind of painful situation deciding just to tend to themselves rather than create a situation where they'd have to tend to themselves and another person without getting any tending in return.

Note: I am in no way unsympathetic to men whose partners have miscarried, nor am I saying that the men should be doing all the supporting, etc (awkward phrasing, but you know what I mean). I would, however, side-eye anyone who didn't give at least as much comfort to the person who miscarried as they accepted from said person. The fact that she hadn't yet told him she was even pregnant sets of some faint alarm bells, though.

That said, OMG, do NOT make this situation into a test/reckoning/whatever. IF this situation has led LW to confront the idea that she can't really rely on husband for emotional support, then that's a thing to be discussed in therapy, first individual, then maybe couples, but do NOT make any life-altering decisions right now, and don't have any confrontations right now. Bad idea, bad!