I think that you are likely to get seats together, even if they are not available at OLCI. There are likely to be some cancellations at the last minute. So if you do not get seats together do not print your boarding passes and keep checking OLCI, changing your seats when a pair become available.
Ask at the gate as well, and even on board as the crew might be able to help.
Remember that two seats across the aisle are as good as two seats together, but many of the aisle seats are misaligned.
The aligned seats are in rows 60 - 62 on the upper deck and 13 and 14 B and D seats in the forward cabin of the main deck only. 13 and 14 G and J are not aligned. 17 - 20 are not aligned.