Thanks both. Being with my partner on the same page is a problem in this particular case (and just a couple of others). It looks as if different, higher priorities overruled all of our spoken and unspoken agreements, and as if a cold and destructive, and otherwise latent persona took over in her, revealing disappointment and contempt dating back to her problems in childhood: the same accusations and demands expressed in an impatient, uncompromising way.

Her son is the only person in the presence of whom my partner has been repeatitively disloyal to me, even making sexually underpinned jokes or comments and persistently denying any link to me, refusing to acknowledge how I feel when this happens, and promoting his behaviour of this kind in a hardly concealed way.

I suppose the reason for all this may be how her relationship with her son's father gradually ended with the child was born. I wonder, if her behaviour towards her husband was anything near what she is doing to me, I would have left without ever looking back.

Unemployment might not be the highest risk because he has turned out to be a reliable, appreciated and committed worker in his first job, whis he has had for a long time now.

There are basically two ways to approach the situation:

1. Preventing it completely by undermining any attempts of the mother to bring her child - this would require a lot of manipulation - and its efficacy depends on how the son will handle his life: if he grows independent and starts a family, that will solve the problem, and I wonder how it would relapse then, because what is happening clearly points to some issues in my and my partner's relationship.

2. Allowing the kid to move in and try to use diplomacy and communication to solve problems as they arise. This may not work, though, because of the apparent lack of trust and a burden of past inflammations.

Looks like I need to choose to be street smart?