What should she do about her husband who talks to women on his mobile phone and asks for their pictures?

Praise
be to Allah 

Undoubtedly this thing that you mention is a great calamity
and is one of the fitnahs or turmoils that may befall a stable and peaceful
family. Therefore, you have to handle this matter wisely and sensibly, and
you should not collapse because of it or do anything that will lead to
regrettable consequences. 

This foolish behaviour may be something temporary, that has
overtaken him because of heedlessness on his part, in which case all that is
needed is a reminder. 

As you say that he is a man who is kind and has a good
attitude towards you and your children, then you should make the most of
these good characteristics to turn him away from this problem and bring him
back to his senses. 

My advice to you is as follows: 

·       
Get closer to him and treat
him kindly, as if he had not done anything. 

·       
Beautify yourself for him at
home, and wear adornment and perfume, because that which is halal and good
prevents that which is haram and evil. 

·       
Offer a lot of supplication
and beseech Allah to guide him and avert evil from him. 

·       
Do not let this matter come
between you and him, or reduce your love and respect for him. Rather make it
a means of you becoming closer to him and more caring towards him. No doubt
he is dear to you and you love good for him, and you hate evil for him.
Right now he is in the greatest need of you loving him more and being closer
to him, so do not leave him to the Shaytan to control him. 

·       
Remind him of Allah and warn
him of the punishment and negative consequences of sin, without letting him
realise that you know anything. You can do that by quoting verses of Quran
and Prophetic hadiths. But if you know that direct exhortation from you may
not be appropriate or may not have any effect on him, then you can seek help
by using moving clips that you can try to tell him about, or put them on his
computer, or send them to him in a text, and so on. 

·       
You can also use Islamic
pamphlets that encourage one to fear Allah and to keep away from sin and
causes of temptation, especially the temptation of women. 

·       
Remind him about his sons
and daughters, and that righteousness of sons and daughters stems from
righteousness of the father and mother. How many men have been tested and
had problems with their children because of sins that they committed, for
Allah, may He be glorified and exalted, will make a man’s offspring
righteous as a result of the father’s righteousness and good care of his
children. 

·       
Remind him of Allah, and of
how He will expose people before the witnesses on the Day of Resurrection,
and He may expose them in this world too, because of their daring to commit
sin in private, not caring that Allah is watching, transgressing the limits
of Allah and daring to do that which He has forbidden. 

·       
Tell him that among this
ummah there are some who will come on the Day of Resurrection with good
deeds like mountains, but Allah will make them like scattered dust, because
of their transgressing the sacred limits of Allah in secret, as was narrated
by Ibn Majah (4245) from Thawban, from the Prophet (blessings and peace of
Allah be upon him) who said: “I certainly know people of my ummah who will
come on the Day of Resurrection with good deeds like the mountains of
Tihamah, but Allah will make them like scattered dust.” Thawban said: O
Messenger of Allah, describe them to us and tell us more, so that we will
not become of them unknowingly. He said: “They are your brothers and from
your race, worshipping at night as you do, but they will be people who, when
they are alone, transgress the sacred limits of Allah.”. Classed as saheeh
by al-Albani in Saheeh Ibn Majah.

·       
Tell him that it is shameful
for a person to feel shy before people but not to feel shy before Allah,
meaning that when he is alone he does acts of disobedience towards Allah,
not caring that Allah can see him. Allah, may He be exalted, says
(interpretation of the meaning): “They
may hide (their crimes) from men, but they cannot hide (them) from Allah,
for He is with them (by His Knowledge), when they plot by night in words
that He does not approve”
[an-Nisa; 4:108]. 

·       
Whenever you find an
opportunity, advise and remind him, without letting him realise that you
know anything. If he does not respond to that and the advice has no effect
on him, then tell him what you know and what you have found out about, and
remind him again of Allah. Warn him of punishment in this world and the
Hereafter, and tell him that the gate of repentance is open to the sinners,
and that Allah, may He be exalted, is abundant in forgiveness: He stretches
out His hand by night to accept the repentance of those who sinned during
the day, and he stretches out His hand by day to accept the repentance of
those who sinned by night. Every son of Adam sins, and the best of those who
sin are those who repent.

All of that should be in an atmosphere of gentle openness and
compassionate rebuke, without being harsh.

We hope that by the grace of Allah, the Most Kind, the Most
Merciful, your husband will come back to the path of obedience and guidance,
and will be diverted from the ways and temptation of the Shaytan, and that
Allah will make him a good husband for you and make you a good wife for him.

For more information, please see the answers to questions no.
150638 and 170662

And Allah knows best.