Our son is 23 and has recently moved in with his GF of three years and his parents not far from us. We have not met them at all. They appear to have welcomed our boy with open arms and treat him as one of the family. Our son works and pays them keep. My husband (who is much more sociable than me) feels we should ask them round maybe for lunch to meet them but I say what for it's not as if they're engaged or anything .. and wondering if it might be awkward. If we don't would it seem to be stand-offish of us? He's our only child and we are not sure of etiquette here - but feel they are nice people and have been especially welcoming to our son.