Wondering about other peoples uteruses..

I was just thinking about my neighbors.. They are cute couple.. a bit older than DH and I.. probably mid-thirties.. I am not sure how long they've been married.. but its been awhile.. 5 or 6 years at least.. I'd say..
But.. No kids.. I mean.. its completely possible that they don't want kids, or are just waiting a little bit.. but now I can't help but wonder if they are dealing with IF or m/c too.. The wife is way quiet.. I hardly ever see her or talk to her.. So its not like I can go ask them.. I never really thought that way about them before we started TTC and stuff.. I just assumed they didn't want kids.. but now my assumptions have changed..
I think that when I see couples without kids now I'm always going to wonder if they are dealing with what I have been dealing with..
Then I had a vision of running into them in the RE's waiting room.. That would be embarrassing..