My bf and I have been together for a year. My sister doesn't really particularly like my bf, but is mostly cordial. 

Yesterday was her birthday and she invited me, my mom, and her boyfriend out to eat dinner as a birthday celebration. When I got off work, I texted my boyfriend that I was going out to eat with all of them when he asked me what I was doing and his response was, "Thanks for the invite". He was literally upset he wasn't invited to dinner and I tried to explain that it wasn't my place to extend my invite to him especially if I wasn't paying. He couldn't understand and for an hour he was bitter, and eventually altogether just stopped texting me until around 12 with some stupid emojis? 

Now my question is, am I wrong? Is it wrong to go places with other people without asking the host or whoever invited me if I could invite him?
user
my bf is upset he wasn't invited to my sister's birthday and
assistant
My bf and I have been together for a year. My sister doesn't really particularly like my bf, but is mostly cordial. 

Yesterday was her birthday and she invited me, my mom, and her boyfriend out to eat dinner as a birthday celebration. When I got off work, I texted my boyfriend that I was going out to eat with all of them when he asked me what I was doing and his response was, "Thanks for the invite". He was literally upset he wasn't invited to dinner and I tried to explain that it wasn't my place to extend my invite to him especially if I wasn't paying. He couldn't understand and for an hour he was bitter, and eventually altogether just stopped texting me until around 12 with some stupid emojis? 

Now my question is, am I wrong? Is it wrong to go places with other people without asking the host or whoever invited me if I could invite him?
user
My bf's birthday didn't go as planned and he's bitter about it.
assistant