She kissed her boyfriend’s twin. What now?

She kissed her boyfriend’s twin. What now?

“We had a BBQ at our place with my boyfriend of 6 month’s family. I was feeling a bit tipsy and I went in for a kiss, but I accidentally kissed his identical twin brother.
My boyfriend saw it and now he’s mad that I couldn’t tell them apart. I vaguely remember thinking he looked a little different, but I just thought he changed his clothes. What do I do now?”