I have several college friends that I am inviting to the wedding who I haven't spoken to in a little while. I am not sure if they are dating, or if those who did have significant others are still together. Our guest list is tight (we can only fit 150 people at the reception) and we originally were only going to allow guests to have a +1 if they are in a serious relationship or don't know other people at the wedding.
As long as they know other people at the wedding, is it best to just to invite them without a guest?