My 19 year old sister has lived with me since she was 14. She finished college in June this year, and it was in January that she started seeing a boy who was at the college as an international student. Whilst he was living in the UK with his host family, he would come and sleep over at our house around once a week roughly, from March to June. When college finished in June, he went back to his home country.
My sister has been out to visit him 3 times since June, for 7-10 days each time. She has now asked me if he can come stay with us in January. I have reservations, but settled on agreeing to one week.
I am a VERY quiet and introverted person and don't like sharing my space with people I don't know well. In fact, I wouldn't even typically invite my close friends or family to sleep over unless there was no other option. I allowed the weekly sleep overs before as they would mostly be doing their own thing anyway, and I guess I thought it would fizzle out once he went home so put up with it as a 'short term' thing.
I also now suspect that the relationship is not a healthy one. She's told me about various arguments they've had which I've told her I find worrying, and he seems to try controlling her, not wanting her to go out with friends or wear certain clothes for example. Not that he's successful, but there are frequent attempts/issues that she tells me about which I don't like the sound of.
So, she's just given me some spiel about flights and claimed it's impossible for him to come for 7 days, it would have to be 10 days due to limited flights. I said no, 7 days is what I agreed, I'll go to 8 days max but that's it. She asked why and I told her the exact things I've said above. She left the room crying saying she'll just tell him not to bother coming. As she was walking out I said that I'm pretty sure flights could be arranged for a 7/8 day stay, but she insisted it was impossible.
I have often struggled to 'say no' to her - she had a rough childhood (hence moving in with me at 14) and I know I've been too soft on her before to try and compensate, but now I can't tell if I'm being unreasonable about this or not?!