Son's girlfriend and argument.

Tell him he either stops her coming over and staying for the weekend or he is out. Your house, your rules. You have to be clear - he is paying £25 a week fgs - he has it cushty at home for a low price so he needs to obey the rules.

Crikey, £100 won't even cover council tax, will it? Certainly not council tax plus electric/gas/water/broadband/tv/food/groceries and whatever else I've forgotten!

Does she work ?
what's she spending her money on, as even minimum wage would give her loads of disposable income at this stage in her life.
Perhaps you could call a house meeting between adults and you bring out the bills and show them both what it actually costs.

I would also hate this sort of a situation and would be saying alternate weekends at most , and she brings her own coffee and bag of food shopping

Well no but I wouldn’t have let it get this far either.

You are not alone.
It's an MN thing.
Don't know it at all in real life.
Certainly none of my friends would have it, no more than my parents would have.

20 and 21 and you have lost your home to them.

Tell your son no more or move out.
They both have a total mug made out of you.

I've never understood this attitude. You don't like them in your house and feel invaded and that you had to be hosting, but you're also complaining they spent all their time hiding away in his bedroom. So either they were in your way and you were playing the host, or they weren't in your way at all but you're still somehow mad about it because you wanted to host.

What's your point? OP doesn't like her - would you like to share your home with someone you're not fond of?

I feel sorry for her, she clearly has nowhere to go where she's actually wanted and has no space for herself anywhere in this. At least you get 4 nights a week, she gets nothing.

I think you're being petty about the oven, your son's utility charges to you covers that. She can buy her own coffee and leave it at yours if she wants coffee.

And yes you need to charge your son more. The more he feels it's unfair, the sooner he'll move out.

@DancesLikeAFairy Oh I feel your pain, I had this and it drove me insane! Aside from disliking her - which in itself makes it all the more worse - it's the feeling of being invaded all weekend. A PP took issue with the 'not good enough?'. Err yes, why would you want to share your home with a person who you struggle to find commonalities with, it's bloody excruciating. And to then have to act like a host, on weekend which should be your respite, is too much. I did initially try by trying to coax them out for Sunday lunch, but apparently DS' GF didn't "do Sunday lunch"
Final straw for me was DS bringing out all the used glasses/crockery after their John and Yoko style 'bed in'.
I was quite happy to be the villain as I knew the relationship wouldn't last if I wasn't facilitating what was basically two kids squatting in a room, weekend after weekend...

What a ridiculous comment. A house guest should wait to be offered a coffee - and making six a day is downright greedy.

Well, you don't seem to know that it's rude to not let your house guest make a coffee!

Ultimately, if it is your house, you can ban her, but it seems very unwelcoming.

Nothing you've described indicates that she is behaving unreasonably.

The issue here seems to be that you are clearly on a limited budget but yet your ds isn't contributing enough towards his housekeeping. Change his housekeeping to between £300 and £400 pm and you can easily cover an extra mouth at weekends, whilst he is still getting a very, very good deal in terms of what he is contributing.

A lot of posters are focusing on the financial and, while that is obviously a major issue, someone who isn't my flesh and blood being in my house all weekend every weekend would drive me bat shit crazy!

Try and enjoy having your son nearby... And another young person to nurture. You're so lucky in that respect. It's tough being that age and they are often clueless as to how much things cost. I'd spell it out....The cost of her getting through that amount of coffee/food and it's monetary impact on you. Suggest she gets some beans/ground coffee/pods for herself (aldi not that bad!)..or get her own cafetiere. Ask them to give your Saturday nights back or Sunday mornings? I'd protect the relationship with them though.

Is your son working? If so he needs to pay more rent to cover her if she can’t afford to chip in.

Then she eats at home with her own family and you keep the coffee elsewhere (assuming this is pod style coffee and not nescafe instant.) Leave a cheap instant coffee in the kitchen.

Both of them are working. They can afford to feed themselves at the weekend.

Just buy what you need for yourself and keep it locked up so she has no access to it.

This (in general, not this case). I also don't understand these young adult relationships where people just move in someone's parents house (without discussion). If you still live with your parents, you don't get living alone privileges.

Do you want her to...
Not stay over full stop?
Contribute fairly when she does?
Tidy up her mess & help out?
Stay 1 night instead of full weekend?
Stay EOW?

You need to decide what you want to happen, and then tell them both

If you charge your children that much each month how are they going to be able to save for their own place?

She should definitely be giving something or bringing for the food and coffee.

I've asked her to pay towards meals. She just says that she can't afford it.
Tell her neither can you.

Surely, at the minimum, if you’re providing food, your DS should be giving you £100 a week ? Limit girlfriend to one night a week staying over with a contribution from her of £15, without food.

Me neither. It seems to start with allowing the child too much freedom to have boy/girlfriend sleepovers and then morphs into the young adult child taking absolute liberties by moving the boy/girlfriend in.