To be upset with DP

[TryingMyBest79]

It's my DP's son's 19th birthday at the weekend. We don't live together but have been together 4 years.
AIBU to be upset that he has bought his son a birthday card and says I can't sign it, I have to get a separate one for him?

It's not a big deal to be upset about really is it? As PP have said, he probably wants to buy a 'To My Son' card. If you don't live with your DP how often do you see the son?

I’m 47, my parents have been happily married for 51 years. They still give me separate birthday cards - one from each of them. No big deal.

seems kind of odd after 4 years alright, did he do the same last year and the year before or is this a new thing?

You are the girlfriend of his dad, you're not his mum. You don't live with him or look after him, you're just dating his dad. I've kept all of the cards I've ever received from my mum and dad, and I'm glad that they only asked their new partners to sign them when they had remarried and I had built a really strong relationship with the step parent, not getting everyone they dated after their divorce to sign.

If the card says Son on it yabu as he is not your son.