This is an ongoing dilemma. It is when you receive an invitation to a party or dinner occasion and the invite says it invites you but there is no mention of a partner.
Or now in the age of the internet and social media when you receive an invite to an event and you presume your partner is invited.
So how does that go?
It was always a very clear understanding and not a presumption. When you receive an invite unless it was clearly stated – and partner or and wife or and husband then you obeyed what was written. If only your name was placed on an invitation, then that would mean only you and this is regardless of whether you were with someone or married – it meant only you.
This is happening a lot with wedding invitations because of the enormous costs involved with meals. Often the couple will invite the person they know but not invite the partner or spouse they do not know. This is tricky and mostly because of the expense of the wedding.
So, my ruling is simple. Only go with the specifics of the invitation, be it verbal or written. If it is only me invited, then it is only me who goes. If the invitation is specific about a partner, then I invite someone to come with me.
I have seen enough embarrassing situations where I take the invite (without questioning it) to its letter.