living together + getting married in Catholic church

I've heard it said many times on here that if you're living together, don't lie to the priest about it b/c it's no big deal.

Now, I'm not trying to advocate lying... but are you serious? The priests did not say anything?

I know for a fact (b/c it happened to people I know ) that if you say you are living together at the church where we'll be getting married, they will tell you you must live apart until the wedding or they will not marry you...

Are most priests not saying anything? No lecture or anything? I just fear a big, long discussion about it...

ETA - I'm just curious to hear other people's experiences. We don't feel that there's anything wrong with living together - obviously - and aren't going to change our living status. I'm just curious how others have dealt with this.