Air Europa have announced that you can look at and book their flights on the RyanAir website. I am not too sure what benefit this offers at this time.
If, as and when through ticketing is announced, it will be a different story; but for now booking Air Europa and RyanAir all on the same website, could be confusing at best.
Most dangerous of all, is if some of the "pudding" (aka "metasearch") websites jump on the idea and start extolling the virtues of "self connect" with the result that consumers could be misled into thinking that, as long they board their RyanAir flight, then they are safe for their long-haul Air Europa flight.
The two airlines are wholly separate and distinct, as are any journeys booked with the respective airlines. How much time you need to allow for any given connection does not come under the "minimum connecting time" rules and so, you have to allow for any delays, technical problems, bad weather indeed anything which may mean you do not have enough time (in Madrid - for that from whence Air Europa come and go) to get off your first flight, collect any bags, go through security and check in again for your next flight. The transit lounge is not an option.
RyanAir say that they hope to introduce through ticketing later in the year without specifying actually when (and, one presumes, visa versa with Air Europa) and until such through ticketing comes about, apart from, perhaps, RyanAir deriving some benefit from offering Air Europa flights, the present offering is rather fraught with possible issues.
Through ticketing would be a major departure for RyanAir (or, indeed, any point to point low cost airline). They would need to be responsible for any missed connections and both being EU carriers, could run into significant costs for having to feed and water (and possibly accommodate) any delayed passengers who missed their flight. Given that Air Europa does not fly every day to every destination, then such costs could be highly significant. This may be why RyanAir are being rather vague about the introduction of through ticketing.