Hmmm, is the situation related to dating? interacting with other people? No to both.
You mentioned mertoing more lately in the dark as opposed to light, is that pitch dark? or simply a dimmer area like on a street corner? Both works. In my case, it's more often pitch dark.
Is the trouble you can get out of something that can kill you? physically hurt you? No to both. is it a social faux pas that you can avoid? Normally not.
Is the relevant "trouble" some sort of injury/collision (e.g. tripping over something, walking into a glass wall)? losing some object? No to both.losing one's own sense of direction? Yesish, OTRT. looking funny/stupid to another person? Possibly, but not primarily.
Does one have to be in the process of moving for the need to merto to arise? Assume yes. or conversely, does the need only arise when standing still? No. Would it ever be necessary to merto in the middle of a wide open field or dirt lot, with no obstacles of any kind within touching distance, and no objects for anything to be hidden behind? Yes. Is any kind of clothing relevant (for example, if it had to do with checking to see if your shoelaces are untied)? No. Is it possible to "incorrectly" merto, in the sense that even though the mental process happens, it doesn't manage to avert the trouble? Yes, absolutely.