My dad met someone after my mum died and was very happy for 17 years with her until she died.
He then moved back to his own home and his new cleaner, looked like Goldie Hawn and was herself very well off and younger than me.
They had a love affair that gave him a new lease of life. Turbulent it was, like a teenage affair, she kept him on his toes.
My sister didn't like it but dad was happy and I was happy for him.
The new lady in your dad's life is also bereaved and may feel insecure and nervous. She sounds a bit like the old ladies in 'Last of the Summer Wine' some old girls are a bit like that proprietorial.
I have a friend who is experiencing exactly the same feelings about her father's new relationship, when I ask her if he can live with her she shudders, she just want to get rid of the new woman, as she doesn't take to her. Would you rather that your dad was lonely?
OK there are gold diggers out there, we are all at risk of being in reltionships where we may be exploited, whatever our age.
If your dad is of sound mind and happy, what he does with his time, affections and money is his business.
Our 'Goldie Hawn' saw my dad through some very hard times and I shall always be grateful, that he had that last fall of romance and excitement in his life.
I would pop round to see your dad often and make his new lady feel valued, you may be glad of her in time. It is hard to settle into the culture of another family especially after bereavment, you, your siblings and dad are all grieving the same person, anyone new will struggle to find the right space. She probably feels awkward.
I did worry that my dad was 'down' sometimes when he rowed with Goldie but who wouldn't want to revisit the vitality of love, when the alternative was watching Countdown??