Mr and Mrs Alden , Mr and Mrs Brent , Mr and Mrs Crown , Mr and Mrs Drake were seated around a table.

Their chairs were arranged around the square table like this:

                         a   b
                     +---+---+---+
                     |   |   |   |
                   h +---+---+---+ c
                     |   |   |   | 
                   g +---+---+---+ d
                     |   |   |   |  
                     +---+---+---+
                         f   e
                                          

For example, persons sitting at positions b and c are considered next to each other.

1. The person sitting across from Mrs Alden was a man who sat on Mr Brent's immediate left.
2. The person sitting on Mrs Crown's immediate left was a man who sat across from Mr Drake.
3. Only one couple did not sit next to each other & this couple did not sit across from each other.

Which couple did not sit next to each other?