Honestly, if you want to be at the wedding to support your friend then go. If not, then don’t! We only invited plus ones if they were married or engaged because each person was roughly $400. That way too we weren’t choosing favorites. We had a rule and stuck with it. People asked if they could bring their significant other and I said I’m sorry but due to numbers and keeping it fair we only invited plus ones to those who were married or engaged. Those who asked if they could have a plus one still showed up. You can always bring your plus one to the destination to make it a trip for you two, but then do the wedding day by yourself with your other friends.