HELP!!! female relationship advice required!!?

i'm a 20 year old lad and my girlfriend is 18 and she shares a bedroom with her 19 year old sister. im looking for advice from a female perspective as to whether im being jealous and insecure or if i am actually fair with my comments. i have been with my girlfriend (gf) for 6 months and we have a really strong relationship and over the past 2 weeks my gf's sister has started dating a lad (a mate of mine) but as of yet are still not in a relationship. However, i have still never slept at my gf's house and whenever we watch a dvd together it is always at my house as she says it is not fair on her sister having me round all the time which at first i was ok with as it is fair enough. However, now her sister with a lad she is not even dating constantly has her lad round for dvd nights and he has even started sleeping at her house whether my gf is home or not and i only get invited if her sister is not sleeping at home which the majority of time she does sleep at home! this has started to cause arguments as i have said it is unfair that she lets her sister have lads round if her sister never lets her but she disagrees and says i am being unreasonable! after we had been together 4 months all of her family and I went out for a meal and drinks for her 18th and i went back to her house with her and stayed till 4am when i rang for a taxi as it was the worst rain storm of the year but no more taxi were still running at this time and so i had to walk 20 minutes home in the terrible weather and early hours of the morning as she said its not fair me staying on her sister not even on the downstairs sofa! yet then i hear her sister is invited her lad round after knowing him 2 weeks and arranging for him to stay and my gf says that its ok! also while we have been together my gfs ex has stayed at her house and i am yet to stay! my gfs mum does not mind and said i could stay as much as i liked if her sister is ok with it! am i being unreasonable in being upset and annoyed at these circumstances or am i just being jealous and insecure?! Please HELP!HELP!!! female relationship advice required!!?
She seems to be shy or have other issues concerning you staying in her home. There could be a million reasons behind. Her sister is more brazen and daring and there is clearly nothing holding her back, but your girlfriend in different.





For you to pressure her about it can actually make it worse, depending on what her reason is.





Just guessing here... I can see it as the home being the safe territory for her and having you in her home at night sleeping makes her feel insecure. It could be as simple as something someone once said that hurt that's now making her insecure. A bad joke, a snide remark or down right bullying. She might not consciously know exactly what it is any more or she might feel silly and she doesn't dare to tell it because she's afraid to be ridiculed. It could also be a fear of sexuality even though you wouldn't have sex. Sleeping over is one step closer to the reality of it. If you are already having sex then it could be a fear of being ';out'; about it to her family.





Only she knows or can figure it out.





Take it calmly, don't pressure her or make accusations she needs to feel secure with you and she knows that you will understand. Ask her about what she feels about it, how she is thinking and in what ways she feels different from her sister. It could be as simple as being shy in front of the family.