It turns out that even monkeys are able to feel jealous of their partners around other males. Jealousy arose in the course of evolution as a way to maintain the integrity of the couple. A man is wired so that subconsciously he wants to declare his rights to a woman and to be the only “owner” of her beauty. Therefore, it is quite natural that your man starts to get nervous when someone pays attention to you. But people, of course, are not monkeys, and bouts of excessive jealousy will only harm the relationship.
But when a man is absolutely indifferent to the signs of attention that other men show his lady, this is an alarming sign. He no longer wants to fight for her and doesn’t want to try to become better to stay the best for her.