Romance companions that hate you?

Whilst I haven't done this myself, I think it is possible to start the romance early, through having high enough approval, and then have it drop low enough later in the game to have a crisis point.

I have seen on You Tube where the PC punches Dorian and he responds by saying "So much for us". This was near the end of the game because he had been criticising the Inquisitor for killing Abelas and his sentinels. Presumably there had been some other decisions, for example exiling the Wardens, that he had not approved of and so this had gone down from the time that the romance started. If the PC hadn't punched him, then presumably the romance would have continued but likely Dorian wouldn't have stuck around after the party at Skyhold.

Regardless of approval you can also get an ultimatum from Sera if you are en elf concerning your faith in the Creators.

DAI differs from DA2 in that you can have approval drop down again at any point through the game, unlike DA2 where once you were locked in as either a friend or rival, nothing was going to affect that state. This was particularly noticeable with Anders where I got locked in as a friend early in Act 2, yet I kept making decisions after that which he ought to have hated but whilst he might rant, it made no difference to my standing with him. From that point of view I prefer DAI.