AIBU for refusing to go on a couples' holiday because my partner didn't want my son to come?

[Jackthecool]

I’m a single dad with full custody of my 7-year-old son. His mum isn't in the picture, so it’s always been just the two of us against the world. I’ve been dating my girlfriend for a year, and while she gets along great with him, she definitely prefers our "adults-only" time when my mum babysits once a week.
For her upcoming milestone birthday, she wants to go on a two-week tropical holiday. I assumed we’d make it a family trip, but she explicitly asked that my son stay behind with my elderly parents so we could have "romantic, uninterrupted time." Two weeks is way too long for me to leave him, especially since he deals with mild separation anxiety, so I told her I could only manage a 3-day weekend alone, or we’d have to bring him along.
She is now furious, claiming I have "no identity outside of being a father," that I'm suffocating my kid, and that she deserves to be a priority for her birthday. My family thinks she's being incredibly short-sighted to expect a single parent to abandon their child for a fortnight, but she feels totally rejected. AIBU for digging my heels i
n?

You are right to prioritise your son. But she's not wrong to have feelings about how she wants to be prioritised; what is wrong is that she is trying to push you to go against your son's needs. It sounds like you aren't compatible I'm afraid. If she wants to be prioritised for her birthday then as you say it's a long weekend max, and then you could also do a two week trip together if she was dead set on that trip. I would worry this isn't the only time she will set this boundary, and that she will expect you to do more and more without your son to meet her needs. Some people always need to be the one who is put first, if she's one of those she is not a suitable stepmother.

Get her gone.

She's selfish, entitled and will never be a good step-parent to your child.

try being single until your child is much much older, OP @Jackthecool