I’ve been in a relationship now with my girlfriend for just over 3 years and living together for just 1 year together with her and her 20yo son. My girlfriend had bought up her son and daughter (a couple of years older and now living away from home) herself and had only had a few relationships for herself during that time.
Originally her son’s behaviour was fine, there was the occasional drunken accident, but he has a job which he has had for 3 years which I thought was impressive based on some of his friends who chopped and changed their minds all the time. We originally lived in village a few miles from a village where most of his friends were and his work so he was heavily dependent on us for lifts as he can’t drive and there was no bus service.

Late last year we moved to the village where is friends and work are and his behaviour has dramatically changed. Without the dependency on us for transport he’ll stay in the pub until after midnight, even on week days and although he denies it he is drinking heavily – previously the curfew based on his need for lifts was 10pm. Often on returning home he’ll help himself to the whatever alcohol is around, even though he has been told repeatedly it’s out of bounds.

On several occasions he’s bought friends back and they’ll sit downstairs watching TV, talking, banging doors etc until the early hours of the morning. Again he has been told this isn’t acceptable and yet continues to do it – my girlfriend and I both work long hours and so being woken up at 3am isn’t what we need.
Also he borrows money promising to pay it back and rarely does. He doesn’t pay any rent whatsoever and does nothing to help around the house.
Up until now I’ve not really had to intervene or confront him as his behaviour was fine before we moved.

But over the last few months I’ve had enough of this consistently poor and inconsiderate behaviour. The matter is compounded by the fact that whilst my girlfriend admits in having wished someone else was there to share the burden of setting boundaries through the years she is very independent and when I start commenting negatively on her son’s behaviour she gets defensive towards him – this has now got the point where she’ll side with her son rather than me.
I think part of the problem is that he hasn’t had boundaries, there was a natural one with the need for us to give him lifts, and I’m not sure how you set boundaries for someone of that age who appears to have managed reasonably well so far without them.

One of the problems that I see is there are no consequences for his actions, he occasionally says sorry, which in reality is more of a token gesture than him actually being sincere as the behaviour repeats a couple of weeks later but if he drinks bottles of wine he doesn’t replace them, although I feel that is almost acceptance of the action in the first place. He also has very immature negotiation skills resorting to the “nag factor” as soon as anything is denied him, which obviously has more chance of working on my girlfriend than me and it’s interesting to notice that when he is doing it he regresses into a childlike voice and posture in an effort to put extra guilt on my girlfriend.

One thing to mention is that I’ve never had kids of my own and so I am relatively inexperienced in terms of knowing how to manage this sort of thing or understanding what behaviour can be expected (as I’ve already said his behaviour previously was fine).

So any help or comments would be very much appreciated...