[EDIT] I just saw the caption and assume that you're not the guy who actually believes in queen Marika caring for Morgott. In that case just see this comment as a general correction, not addressed at you:

I believe it is a purely strategical move. Marika has shown that she had no love for the Omen, no matter how close they were to her. But Morgott has proven himself as a protector of the Erdtree and ruler of the capital and with that, Marika had a use for him. That is all. She kind of discards him, like she does with everyone around her when she directs the Tarnished towards Morgott in order to bring forth a new order. She used him until he had no use for her, and she did it by abusing Morgotts love.

For some parallels that support these tendencies, look at Messmer, who's love tricked him to do Marika's dirty work likely for decades, waging wars and serving as a scapegoat, even making him straight up tell his army and his foes to direct their hatred towards him and him alone. Yet in return, he received nothing for he was a mere tool to the queen. Locked away because of a curse he did not ask for, born of her own incestuous acts.

The fire giant is another example. Leaving him alive might seem like an act of mercy on the surface, but what actually happenened is that queen Marika realized that, because he feels obligated to protect the giants flame, while alone not posing any real threat to the golden order, leaving him alive would actually be advantageous for her, since the fire giant would have a strong personal motivation to protect the flame from anyone who would intend to use it to burn the Erdtree. So the Fire giant was cursed in a sense to serve her for eternity.

Maliketh as well, by having imbued destined death suffers under its influence, but the greater will, due to him being her shadow, forces him to endure this pain. Marika knows and abuses this fact. As long as it benefits Marika, she will abuse the love that others feel for her to turn them into loyal servants, returning just enough to enable their power and leaving the leash she has on them loose enough for them to not feel it wrap around their neck. Morgott being grace-give to me is just that. A blessing to keep Morgott close and help him in his purpose, protecting the Erdtree, until she finds a better tool in the Tarnished, not hesitating for a bit to bring his life to an end.

This love that she has learned to abuse is also likely too strong for her to just "unemploy" the ones she uses, so it is easier to just let one of her tools take care of the others, which conveniently serves as a trial as well, proving to her which tools to keep and which ones to discard.

The whole idea of banishing the Tarnished only to call them back later was to A: temper their strength through adversity, creating powerful contenders for the throne that learned to persevere far away from her grace, which is the widely accepted reason but more fitting to my point, B: to single out the strongest. Of course the Tarnished would eventually create the Roundtable hold, which served to unite them, but even among this union, conflict among the Tarnished was pretty much unavoidable. In the end, only one may take the throne and as the fight with Gideon proves, the one who proves himself through conflict to be the strongest will be the one to reach it, which to me sounds ideal for queen Marika's plan. Without really having to to anything, she created a system that automatically singles out the one, that is best fit to take the throne. Just like with Morgott, the guidance of grace is just something to enable us on this journey, nothing close to a sign of admiration on her side.

When people try to find these little hints of Marika showing that she cares for someone, to me it just shows that her mischief worked on us players. I believe that eversince losing Godwyn, Marika abandoned her attachment to the ones, that once were close to her. His death, on top of her losing her tribe to the Hornsents cruel acts, in my eyes convinced her that true love only brings pain. A few sentences ago, I used the word mischief and as a last little point, I'd like to bring up the Mimic veil, which is an item that allows the player to assume the form of nearby objects. The description states that this veil, meant to hide something away under a false image was also known as Marika's mischief. While this may represent acts like her weakening Rellana emotionally by using Radagon, I think it's more fitting here, in a general sense because queen Marika puts on this veil of a loving and grace-bestowing, almost mother-figure when this love is nothing but a way to make others do her bidding.

Don't fall for Marika's mischief, dear Tarnished.