I think the bride is rude, guests should feel welcome and comfortable,
It's a red herring have a new boyfriend, so what ?
It is normal to have a plus one, someone who is there as your companion, you will end up being expected to entertain some elderly loan relative.
It a very odd thing to do make someone be alone when they don't have to be,
It's more enjoyable when you have someone to reflect with, have a dance with,
the thing is not only is she making you feel uncomfortable, she will be making your boyfriend feel uncomfortable,
Is she normally so selfish, or is this a bride thing?
I wonder how she would of felt a few years back, if it was you getting married, and you didn't invite her boyfriend, the one she is about to marry, it will be awkward in a few years time if you two decided to get married, would she come, be as she rejected him as no relevance now.
Either she hasn't thought it through, doesn't give a jobbie, wants you to fancy her brother/cousin or she thinks she has a crystal ball and thinks she doesn't see your boyfriend in yours or hers future.
so basically she rude.