Primes are fine, but I wouldn't want to shoot a wedding without a 50 mm focal length.
I love to hear why? I am currently looking for adding 50 or 85mm and like to hear your arguments.
Space, distance and perspective are my reasons for this. 85mm gives a pleasant perspective but you need to be able to get far enough away. You also need more light one way or another to keep more depth of field. 35mm will result in an undesired perspective when used close; to reduce depth of field you're going to be very close = undesired perspective. In these situations the 50mm (on FF) gives you a pleasant, neutral perspective even when close, and you have good control over depth of field. That's why I say I wouldn't like to shoot a wedding without access to the 50mm focal length.
I don't know what you shoot or your style but I see you have the 135 so if deciding between a 50 and 85 prime, I'd go for the 50. You hear people say it's a 'boring' focal length because it doesn't give an exaggerated perspective either side of neutral, but I have found that relying on extreme perspective to make a picture good is a mistake.