Worried about sons girlfriends

[Alicemomof2sons]

I have 2 sons. 19 and 17. They are both in relationships with girls of the same age. My eldest had been with his a yearand my youngest with his 2 years. They are both lovely girls but I feel like there are some problems between them. The eldests girlfriend had basically lived with us from the day they got together until my son went on a week holiday in August whilst the youngests parents were very strict and wouldn't let her stay over or even come over most week nights until she had left school and didn't let her stay until after her 16th birthday in the summer. I feel like this made her very jealous of the elder girl. When my son left for his holiday his gf obviously went home for the time my son was a away but we still chatted threw texts and Facebook regually. One day I got told by my younger son and his girlfriend that my elder son and his gf had been smoking in the house while I was away the week before he left for his holiday, I then searched his room and found fag butts and 3 bottles of half drank flavoured vodka in his room and 2 empty litre cider bottles in the recycling. My son and his girlfriend were 18 at the time so it was perfectly legal but I was obviously fuming as I would never allow smoking actually inside the house and I had never known my son to be smoking or drinking like that so out of anger I blamed the girlfriend and said she was no longer welcome. I never discussed this with her as I wanted to talk to her and my son together when he got home. No more than 2/3 days later the girlfriend received a very nasty text calling her a drug addict and alcoholic and loads of other nastiness and saying she was no longer allowed in my house. Upset by this she sent me screenshots of the text and explained that she wasn't like that, after speaking to her mum I came to the understanding that she wasn't a big drinker and she has never been a smoker either. I apologised to the gf and explained that I was angry and I know it wasn't her fault, all was forgiven. Until a few hours later when the gf found out how this misterious texter got this information. My youngests girlfriend has sent one of her friends a screenshot of a conversation between her and my son in which she had blamed the elder girl for my sons behaviour and my younger son had told her I had said she was no longer welcome. They both denied all knowledge of this screenshot being sent. I left it as that as the elder girlfriend was happy as long a i knew the truth about her and didn't want to cause problems.
A week later my son returned from his holiday and I assumed everything would go back to normal with his girlfriend. But it didn't, she tells my son she does not feel welcome in the house anymore and she hasn't stayed over since before the holiday. On the days she does come over she spends a lot of time downstairs watching tv and gossiping with me but as soon as my younger son and his girlfriend come home she hides away in my sons room or even leaves to go home. This is very upsetting for me as she had become like a daughter to me and I do miss her a lot.
Recently it had come to my attention that the younger gf actually did know about the the text that had got sent and the people she had denied knowing actually turned out to be some of her and my sons friends. I also hear a lot of the time the younger girlfriend making remarks and sometime quite bitchy comments about the elder girlfriend. I just don't know what to do as I love both the girls and I have a good relationship with both but there is obviously problems between them that neither are willing to sort, either out of fear of causing to much drama or just not wanting too and lying about it.

I'm also having a lot of problems with the younger girl recently. She has started to be quite rude to me and my partner, disobeying us and lying to us. She has also started upsetting my son by being very controlling and not letting him have a social life out side of her.
Would it make sense to just tell her that she can't spend as much time over ours now? As she is spending most nights here. To give the elder girl a chance to come back into the family and start spending more time with us and also to give my son a break from her. Or would this cause more problems?
I really need some advice as o don't have experience with this at all as this is both their first real relationships.

[corythatwas]

The first thing that seems clear is that you messed up badly about the elder girlfriend. To come home and find evidence of something you do not allow in the house and immediately jump to the conclusion that it is her fault and not your precious child's is very unfair. I would not want to go back to a house where I was treated like that. Bull in a china shop doesn't cover it. You have some serious bridge building to do here she is ever to trust you again.

(have you even explained the rules clearly and calmly in advance? an 18yo would not necessarily know they are not allowed to drink in your house)

That seems to make it even more important that you don't go charging in over the younger girlfriend. It seems pretty obvious that she has behaved badly, but the only way to deal with it is to be calm and sensible and rational. Have a private conversation where you explain that you know you behaved badly over the earlier matter but that you do want to maintain certain standards in the house and that fond as you are of her you cannot accept rudeness either to yourself or to your elder son's girlfriend.

And do try to step back a little generally, perhaps. Regarding such young girlfriends as daughters is perhaps a little premature to start thinking of them as daughters: they are unlikely to end up in permanent relationships with your sons. And they did it would not be for you to manage their relationships. Make sure you build up your younger son's self confidence so he knows he doesn't have to take rudeness or controlling, but also make it clear that he has to decide if this is for him. You insist on house rules but nothing else.