I think this has to have a lot of variation depending on where someone is at with their current life. How busy, how "full" as we often refer to it etc.
I think it's hard to draw a line between "looking" (actively in some way) and being open and aware.
There seems to be lulls- quiet periods - in any relationships where everyone becomes part of a conversation such as - "you know - it might be nice IF....." - and you can fill in the "if" appropriately.
When these points occur - these conversations come up - it just seems to put everyone into some heightened state of awareness of other potential connections.
Is this "looking" - I suppose so in some form.
Is it because of some "lack" - well I suppose someone might define it that way too. But in reality I don't think it's quite like that. It just seems to be more like - well I have these fries here - maybe some ketchup would go nicely too.........