He is away from his country and his wife and he wants to take a second wife
There is nothing wrong with a man taking a second wife if he is financially and physically able for that. But before you go ahead with this marriage, it is essential for you to note the following:
It is not permissible for a man to be away from his wife for more than four months except with her permission; and if she does not give permission then he must bring her to join him or go back to her.
It says in Fataawa al-Lajnah al-Daa’imah (19/469): The period during which it is permissible to be away from the wife is four months; this is known as the eela’ period. Staying away for longer than that is haraam, unless it is done with her consent. End quote.
Shaykh Ibn ‘Uthaymeen said: Part of kind treatment is for him not to be away from his wife for a long time, because it is her right to enjoy intimacy with her husband as it is his right to enjoy intimacy with her. But if she agrees to his absence, even for a long time, then she has the right to do so and there is no blame on the husband. But that is on condition that he leaves her in a safe place where there is no fear for her. End quote. Fataawa Noor ‘ala al-Darb, 10/307
See also the answer to question no. 102311.
One of the conditions of its being permissible to take a second wife is fair treatment of both wives, because Allah says (interpretation of the meaning):
“but if you fear that you shall not be able to deal justly (with them), then only one”
What is meant by fairness or justice here is treating them equally in terms of spending, clothing, accommodation and other material matters. How are you going to achieve fairness between the two wives when one of them will be living with you all the time and you will not see the other one except every two years for a short time?
Unless your first wife agrees and gives up her rights to time with you during this lengthy period.
Ibn Qudaamah (may Allah have mercy on him) said: If he has two wives in two different countries, then he must treat them fairly, because he has chosen to keep them far apart from one another, but their rights are not waived as a result of that. He must either go to the one that is far away on the day that is hers, or bring her, or bring both of them to live in one city.
If she refuses to come even though she is able to, then she forfeits her rights because of her defiance (nushooz).
If he decides to divide his time between both of them in their own cities or countries, and it is not possible to divide his time between them night by night, then he should make the period spent with each one of them according to what is possible, such as one month with one and one month with the other, or more or less than that, according to what he is able to do and depending on how near or far the two cities are from one another.
End quote from al-Mughni (8/152)
To sum up: it is permissible for you to take a second wife if your first wife agrees to you being away from her for a long time and she waives her rights to time with you during this period. But if she does not agree, then you do not have the right to go ahead with this marriage because you are not able to treat both wives fairly and justly.
What you should do is strive hard to bring your wife to join you. If you can do that and then after that you want to take a second wife, then there is nothing wrong with it.
And Allah knows best.