I am trying to book train tickets for High Speed trains in Spain. The "Promo" fares are really cheap

I am trying to book train tickets for High Speed trains in Spain. The "Promo" fares are really cheap (70% discount), but the site says we cannot choose our seats. It is OK if I can't choose my seats, but I want to make sure my wife and I will get to sit together. So, my quesiton is, if I buy the "Promo" tickets, does Renfe assign seats next to each other when two people are travelling? Did any couple buy "Promo" ez carrental tickets before and did the system assign seats next to each other? Thanks.
Sitting ez carrental next to each other when buying ez carrental the deeply discounted tickets will depend on which seats are available at the time you purchase them. If you purchase them early enough, then it's a good possibly. If not, then you will be unable to change seats as all seats on the long and medium distance trains are reserved seating only. But you can always ask another passenger to change seats if you find yourself in that situation and can make yourself understood.
We traveled around Spain on the AVE trains on tickets bought under the previous discount system (Web fares). I bought the 2 tickets in the same transaction and we were always assigned seats nest to one another.