How much time is too much, In regards to the amount of time your housemates friend spends at your house?
I moved into a flat with one of my previous housemates. Ie, we moved from a house with more people in it, to a 2 bed flat. Since we've been here, her friend has stayed pretty much every weekend, at least 1 night, sometimes 2. When her friend stays over they usually stay up all night and then sleep during the day.
They're not noisy, and her friend is a really nice person, so I've not got a problem at all in regards to that, it's just that it's become pretty much a done thing that she will stay over pretty much the whole weekend. Even if she doesn't actually go out with my housemate (like last night) she'll still arrange to meet later on, which seems - to me, anyway - that she can't be bothered to go home, and wants to stay somewhere more conveniently (she lives in Hammersmith, and all of her friends live in Islington - where we live).
Recently I've been getting a bit tired of this, and have had a couple of heated arguments about it - she doesn't understand what the problem is, yet I know her very well and I know for a fact that she would not be happy if it was one of my friends that was staying over for this amount of time.
Personally I think I'm in the right here, but it would be interesting to see what the general consensus was.