You have a good intuition. I don't like him, he is very unstable (sth we will see quite soon)
No. He’s a yandere.
He will become one later on. But Idk If he even is a Yandere, It was said that he is just obsessed that's why his bar will never reach 100, because It's not a true love
and thats on Stockholm syndrome
He’s a masochist.
Did no one notice the small glance he sent to her ring while he was kissing her hand??? I can assure you all, he's gonna be up to something. He might even attack her. Also, don't hate on her brothers so much. At those times, going out during the night and appearing with random man would be very bad. I'm not justifying them but if you just appeared with stranger at your Parents home and gave no explanation then wouldn't it be bad.