Hi @PurpleLampShades
"They did come over for Xmas day. I had asked DS what some of gf’s favourite drinks/food are so he asked her and then gave me a list. Of course, it was all expensive stuff. I spent £27 on a bottle of champagne only for her to declare (fake) apologetically that it was the wrong one and she couldn’t drink the one I’d bought. She then preceded to gaslight DS into believing he’d got it wrong, rather than the fact she deliberately told him the wrong one, so he spent an hour apologising and waiting on her to make it up to her. Then she couldn’t eat the meat because it was ‘lovely but just a bit too salty for me’. Again, with the fake, sad smile and apology.
She spent the time here monopolising DS and ordering him around. Most uncomfortably, she was all over him, kissing, touching, whispering in his ear, practically in his lap. I had to keep leaving the room to go to the kitchen to avoid it. I even overheard her telling him she wanted to have sex with him in his old bed, though she said it a bit more vulgar than that. I hid in my bedroom for a while with a large gin as I could feel myself getting more and more pissed off with her.
They were here for about 5 hours in total and I barely got a minute alone with DS. I’d like to say it was a lovely time, but it was hideous. I do not want that woman in my house ever again. She is clever and a master manipulator and she has my DS in a tight grip. I don’t know how on earth I’m going to extract him from it."
I agree that someone coming between a parent and child is exhausting, painful and a hideous situation. Were I in the same situation as you I would be pulling my hair out. At the same time, I always want to offer another view (that isn't the "go to" view on MN) and have some thoughts. Please consider them with good intentions...
Firstly what a lovely, thoughtful thing to do for the GF. Many wouldn't have been able to control their anger so well done!
I've highlighted all of the judgmental/emotive stuff and wonder whether you could frame this in objective terms? If she were that good a manipulator you'd have fallen for it, so she can't be as good as all that.
It sounds like you are in a battle here, and the fact is he is going to be a horny teenager, so his genitals are going to win out every time. The more you dig in, the more the GF will have ammunition against you (if that is the intention, I won't make assumptions here).
Could it actually be he forgot the champagne type and the meat WAS a bit too salty? We don't want to assume that everything she says or does is BS, it may be at least partially true. Would you have preferred her to be dishonest and say how lovely everything was? My partner's family put salt on EVERYTHING, whereas my family never seasoned ANYTHING growing up. So a little seasoning for me is like a salt bath!
The sex talk is, however, gross and I think they need reminding that you are his mother and don't need to hear such things. You can be polite about it, just stating the facts and how it isn't comfortable. Remember that it may be that they didn't think you could hear (they were whispering after all) and that they both may see you as an old fuddy duddy!
The learning here is to keep your child(ren) on side and not have them leave the house under a cloud. Play the game, don't cause waves. He will break up with her eventually, he is 16.
In short, yes the whole thing is hideous and painful. If the girlfriend was 17 rather than her actual age, would this be a problem? I am wondering whether the age gap is actually more of an issue than the actual relationship itself. Heck, when I had a partner in my teens then friends, family etc wouldn't hear from me for months!