Is there a difference between "proskollethesetai" vs. "kollomenos"? The first one is in Ephesians 5:31 and the second is I Corinthians 6:16.
The root word is kollao, which means to glue or cement together. Proskollaomai is related to kollao. The prefix pros means to or toward, but doesn't change the meaning of the root. It just makes it more emphatic.