I have a question for one and all females.. no male should answer please..

Being in the IT industry for quite sometime, I have seen guys running behind gals, plead, propose, seduce, love, marry claiming he ll lookafter better than anyone on the earth,, after few months they marry,, they have child,, later as if lightning has struck, the guy starts treating his so called gf, lover, wife as a maid to lookafter his old parents, his kid, his house, everything which belongs to him. But he will be turning his nose to the fragrance of his lady colleague, ex gf, some neighbours,, why dont guys treat gals as human with heart which needs love, compassion , affection. Why he thinks that all women in the world deserves respect and dignity but not his own wife. He is ready to lend his helping hand to someone whom he has seen before few minutes in a mall.. but his hand will not raise even if his wife fall slips..There s lot lot lot ...can some lady answer what makes a guy do this to her..