Visitation Rights

[rose590 at yahoo.com]

No: HPFGUIDX 26212

I've just about finished reading all the books for the second time - 
I only started in July - and there was a particular question that 
came to mind. Please forgive me if this has been discussed before.

Are the students ever permitted to visit each other in their common 
rooms?  

I ask this question for several reasons.  My first thought was no as 
it was mentioned in GoF that those students escorting those from 
other houses to the Yule Ball would meet them in the entrance hall 
(please also forgive me for not having exact quotes as I listened to 
all four books on audio).  Then it occurred to me that several 
students had developed girl/boy relationships outside their houses 
(ex: Percy and Penelope, who by the way we never hear anything about 
again after PoA).  Since it seems as though there really isn't much 
mixing of students outside their houses, wouldn't that also lend 
credence to the argument that MWPP were all in the same house.  After 
all, they would need an awful lot of time together to have planned 
all their escapades and we already know that leaving a common room 
after dark is a violation of school rules.

Thanks
Rose (who thinks she thinks to much and gets easily confused)