I'll post my standard reply to these types of questions:
It really depends on your betta's personality. Some are sweethearts who don't seem to mind having tankmates; others are psychopathic killers who will murder anything that moves (I have both types of bettas).
If your betta has a sweetheart personality, you can try
adding a tankmate. This should be something that in no way resembles another betta (so avoid anything colorful and with long flowy fins).
Keep in mind that if it doesn't work out you will need to remove either the betta or the new tankmate and house them separately. This means that now you will have 2 tanks to care for.