I dont think it has anything to do with the EU, i think it was done by the British gov for those who use the EU route, as under British immigration rules there was the unmarried partner visa, so they recognised the need for one for those using the EU route.
have you lived together for 2yrs 'akin to marriage' ? and have evidence of this? or maybe you could go and live there ???
good luck with what ever you do thou
