fighting

Question
hi ,
i have a 1.5 year old male cat . i had him from the time he was a 2 months old kitten . i brought him a female cat about 4 months ago because i felt he was so lonely and depressed . their relation was so good for all these times . they were all the time looking for each other,chasing each other, playing all the time and calling each other whenever they had lost the other one in house. they had also mated for 2 times of heat period,but it's now about a week that my male cat is chasing the other one just for fighting.he waits until when she moves ( for example she starts walking ) and suddenly jumps up to her. i know that this is not just as a play because i can see his face different from any other time . he makes a sound like : Kuhh Kuhh... moving his mustaches forward. when i want to take him back he bites me. he used to be a very very very calm cat , and now he is, but not about the other cat.he is so shy of the strangers, he escapes the time they enter home so that it's unbelievable for me to see him hurting any other moving thing. moreover, he still calls her when he loses Joli ( my female cat ) . I'm also worried about her because i think she might be pregnant.the only thing I've done is that 2 times i took him to the bathroom and kept him there for 10 minutes in off light, I thought maybe he would understand the punishment.
please guide me , what should i do?

Answer
Dear Camelia,

Cats do this, even when they're best friends. They just fight, and have had enough of each other. Just maybe you could try separating them, and spending a little bit more time with your male cat, he may be jealous. Otherwise, I don't know because he has his own personality. Thanks. Good luck.

-Laiya