Older womans strange friendship with my 13 year old son

[Kangaroo123]

Really not sure where to go with this!

My Ex lives with his GF, her sister is forming a close friendship with my 13 year old son, and it feels increasingly inappropriate. She is single, in her 30s, my son says 'she's always around and kind to me, she looks so young for her age people think she is a teenager too'. He sees more and more of her one to one as my Ex goes to work on his visits.

She's started to contact him a lot on Instagram, leaves lots of kisses and asks where he is, what is he doing etc.

Unfortunately my Ex doesn't speak to me at all and quite hostile, if I tried to diplomaticly speak to him it wouldn't go down well. Any thoughts?

OP I dont think this is normal at all. I hate to ask this but has this woman,got a low mental age?

Another thread about this?

I was going to say, this is very familiar

Whatever her intentions it's very inappropriate

MN is full of it today.

Thanks, i think I needed to check that others also thought it inappropriate. At first it seemed OK as it was, I suppose, extended step family, but it's not feeling right at all anymore. She is apparently a nice woman, normal mental age, no children or partner, a bit of a health freak and hippy and from wealthy family.