At the time I (29F) had been dating my then bf (25M) for two years. We were both living with our parents, basically broke, and I had just opened a business with two friends ("Ellie" 28F, "Janet" 26F) - we were in debt, looking at a few difficult months/years of hard work.
It goes without saying that I wasn't the least bit excited about turning 30: I felt like I had achieved nothing in life, hadn't settled down family- nor work-wise, I felt quite depressed. Plus, I hate birthdays in general so that was going to be really hard. My bf was aware that I also hate surprises, and surprise parties in particular, so I was a bit taken aback when he told me he was going to take me out for dinner for my bday, just the two of us, to a place he had chosen. He never showed much initiative in our relationship, so I was excited about it and bragged with anybody who would listen about the romantic dinner we were going to have.
When the day came, he blindfolded me and then started driving. Something felt off, so I casually asked - we're not driving to Ellie's house, are we?!
You bet we were. Turns out, Ellie and Janet had organized a surprise party and basically bullied him into it saying that "who doesn't like a party?!?" I told him off that night, mainly because I would have liked him to give me the heads up so I could play along, but then acted dumb and didn't spoil the "surprise". At the end of the party, Ellie casually drops the bomb: she's pregnant. Which means the bulk of the newly opened business will fall on my and Janet's shoulders. I couldn't disguise my lack of enthusiasm at that point, but didn't say much and we left shortly after.
For years after that night, Janet and Ellie hinted at the fact that I acted ungrateful ("after throwing a whole party for you, you're not even excited about it?!") and straight up told me that my reaction to the pregnancy announcement wasn't "how a friend is supposed to react".
So, was I the asshole?!