What makes a man lose interest in a woman?

When a girl is so much naughty and irresponsible. And she is like an octopus dating or have relations with two or more men at a time is not good. Men don't like that things.

Hi, i am woman but i ll try to say my opinion...man lose interest in a woman when he know other woman, and want change his partner.
I don t want to say that all man are same, of course that people are different, and are man who want a woman for all life, as a woman like to have many partners or are very faithful.
But man want all time change the woman, if see other woman, more beatiful or more intersting for what he want, he will change very easy his woman. No offence.

I think if the woman stops appreciating what a man does for her, he eventually loses interest in her. According to me, a man whether he is in a relationship or not, always tries to impress the woman. I mean to say, he always wants to show off how perfect he is. Not always but most of the times he has put in lots of efforts in a particular job that he does for his love. But sometimes (again not always) the woman fails to appreciate his doings because of stress or maybe some other important work. This makes a man feel neglected. And if the woman repeats this every time the man does anything for her, he starts thinking that it would make no difference if he did anything for her. So eventually, he stops doing things for her. And as you can see, he starts losing interest in her...
Of course, this is my opinion and there may be some other reasons too.
A very nice discussion...

I would have to say communication problems. Guys have many fantasies about trying new things. Some women are open to that and some are not. In order to actually find out, both parties have to be willing to talk about it. When I say talk about it, I don't mean giving an automatic response of "no" or " I will never do that." If she says "no" he should try to find out why and continue the discussion. A lot of guys would react by saying "ok" when they are really not ok with it at all. This begins the second part of the problem. He begins to look for someone else to share that fantasy with.