DP of 14mths has old female friend who he meets roughly once a fortnight for an hour or two. It used to be weekly but I struggled after seeing texts (I was shown them! But only after I questioned why he was hiding his phone) 3 months ago that implied he'd rather see her than me on one particular occasion...my birthday actually! He had double booked us.
I recognise they have a close relationship and accept this - they've supported each other through seriously hard times in the years before I knew them.
This week I suggested, instead of leaving his house and walking home to give them space for the hour, I stay but leave them alone to chat and go upstairs to have a bath and read my book. DP became irritated, told me I was weird to want to stay and stropped until I packed up and left.
It doesn't help that he's told me they used to have a sexual relationship - she's now living with her partner. He's also told me (several times) he still fancies her, she's not far off 20 years younger than him.
I totally believe nothing is going on between them at the moment but feel wrongfooted and sidelined. Am I being unreasonable to still be pissed off?