Morgana later becomes deeply attached to Mordred, a young druid boy whose life Merlin saved, risking Uther's wrath should their actions be discovered (The Beginning of the End).
She loves Merlin because when she is with him she doesn't feel alone. That's it for part 1.
Morgause genuinely cared for her half-sister Morgana, who seemed to be the only person for whom she had any affection. The two were originally believed to be half-sisters though this remains ambiguous.
Arthur & Morgana
At first it seemed that Morgana had a crush on Arthur and she was always near him and supporting him, Arthur had feelings for her too and he thought that she was beautiful, time after she find out that she was the half sister of Arthur and Arthur was in love with Gwen.
The French Vulgate texts establish the idea that Viviane is Merlin's student as well as the woman that he is in love with. We also learn that Merlin is the son of the devil. Viviane and Merlin are in love, and Viviane wishes to preserve the state of happiness that they are in.
Gwen is still close friends with Merlin, but no longer has any romantic feelings for him.
Morgana Pendragon, 607 - 621
Morgana married Merlin. Merlin was born in 603. They had one son: Arian Pendragon. Morgana passed away in 621, at age 14.
Morgana is older than Arthur, because that's why she believes the throne should be hers, as she is the oldest Pendragon child. Morgana Pendragon is oldest than Arthur with at least 1 year but not more then 2 years.
With the help of her half-sister, Morgana, she sacrificed her life to the depths of the Other World. The resulting chaos proved that even in death, she was a formidable enemy to Camelot.
She seduces Arthur in the hope that she can later use it against him.
Is Merlin, who has and used magic his whole life, who has learned from Giaus and Kilgharrah, and is the only Dragonlord more powerful than Morgana, who slowly learned to use her magic at first, but then had a crash course from Moruause, who had been trained her whole life with those who practiced the old religion..and ...
Arthur, who is no saint himself, has a child out of wedlock – the product of an incestuous union with his half-sister Morgause (in some versions of the legend it is Morgan, but the two have often been conflated, especially in more modern retellings).
Morgan hated Arthur for his purity and unknowing hypocrisy and so plotted with her lover, Sir Accolon, to steal both Excalibur and the British throne. Arthur met Accolon in combat without his magical sword, but the Lady of the Lake Nimue helped him retrieve it and win the battle.
Even in tales where she is the villain, she is still capable of love, and still willing to heal her brother Arthur after all is said and done. Most of Morgan's villainy stems from her hatred of Queen Guinevere, and the desire to bring shame to Camelot which that hatred causes.
When Nimue and Merlin meet in the fifth episode, she asks the wizard why her mother instructed her to bring him the sword. By the end, viewers learn that not only did he and her mother have a relationship, but Nimue is actually Merlin's daughter.
He bends down over Arthur's hand, and he's kissing it softly, pouring all his love and longing into the tender touch of his lips; and then Arthur mumbles a little, sleepy, and Merlin's heart nearly stops. He jolts back, breathing fast, heat flushing his cheeks and face.
He looks for the queen and finds her in a nunnery. For love of Guinevere as much as for remorse he takes on the habit of a priest. Guided by visions, he goes to Almesbury, where he finds Guinevere dead. He buries her beside King Arthur, then sickens and dies himself.
Guinevere is Arthur's wife and queen; according to the Vulgate Cycle and Malory, she is the daughter of Leodegrance of Carmelide. Though one of the Welsh Triads (Triad 56) speaks of Arthur's three great queens (all named Gwenhwyfar), later romance generally gives him only one wife named Guinevere.
Morgana later becomes deeply attached to Mordred, a young druid boy whose life Merlin saved, risking Uther's wrath should their actions be discovered (The Beginning of the End).
Canon Era. gwen gets pregnant and arthur doesnt know about it until after he finds out merlin is dragoon.
Though their courtship was complicated by their differing social classes (and later by interference from Morgana), they were ultimately married in the final episode of series 4. As of Arthur's death in the series finale, Gwen is now his widow and rules Camelot in his stead.
Trivia. Freya is Merlin's only love interest throughout the series.