Praise be to Allah.
If your cousin does not pray apart from Jumu’ah, and he smokes the shisha and sits in coffee shops, then you should not accept him, rather it is not permissible for you to accept him, because if a person does not pray apart from Jumu’ah, the scholars differed as to whether he is a kaafir; some of them said that he is a kaafir, and some said that he is a faasiq (evildoer). At the very least he is committing a major sin.
How can a believing, righteous woman whom Allaah has blessed with guidance and who has become religiously committed and righteous, accept to marry a man like this?!
As for the love to which you refer, it cannot be denied that the best remedy for two who love one another is marriage, but this should not be at the expense of religious commitment, because love may change and disappear, and be followed by hate and harm, especially if the man is heedless of the rights of Allaah.
Marrying a man who is not righteous in the hope that he may be guided in the future is a risk that leads to negative consequences. He may or may not become righteous. You have to imagine what your life would be like with a man who does not pray, and who offends you with the stink of his smoke, and who wastes his time with bad companions in the coffee house.
A person like you is not unaware of the difference between the life of religiously committed people and the life of others who pray and are good in general, so how about life with one who does not pray and who smokes?
If this young man knows that he has been rejected because he does not pray and he smokes, and he does not mend his ways or become righteous, then the hope that he might become righteous after marriage is even more farfetched. No one knows what will happen tomorrow except Allaah, but this is based on general knowledge of how people are. If he really wants to marry you, then he will do everything he can to improve and change his image. If he does not do that, then there is a strong possibility that he may stay as he is after getting married.
Hence we advise you to let him know that you have rejected him because of his shortcomings and negligence with regard to religion, and that the rejection did not come only from your father, but it has in fact come from you too, after suppressing your feelings and following the rulings of sharee’ah on this issue. If he changes and becomes righteous, and that lasts long enough for you to be certain that he is steadfast, then in that case you may accept his proposal, and urge your father to agree.
But if he remains as he is, then stop thinking about him and remember that there are many other men who are righteous. Married life is intended to last for a long time, and it requires both partners to be compatible, so that their life will be good and they will produce righteous offspring and build a good family.
Happiness is not attained just by getting what one wants; rather true happiness is a gift from Allaah, which follows faith and righteous deeds, as Allaah says (interpretation of the meaning):
“Whoever works righteousness — whether male or female — while he (or she) is a true believer (of Islamic Monotheism) verily, to him We will give a good life (in this world with respect, contentment and lawful provision), and We shall pay them certainly a reward in proportion to the best of what they used to do (i.e. Paradise in the Hereafter)”
Hence we see many cases that start with love before marriage, and end in failure and sorrow, because they were not based on obedience to Allaah.
See the answer to question no. 84102 in which there is a social study of this issue.
It is obvious that your cousin is a non-mahram to you like any other non-mahram man, so there can be no relationship between you before marriage. So he should not look, shake hands, be alone with you or engage in conversation in which you speak in a soft voice. Allaah says (interpretation of the meaning):
“…be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner”
We ask Allaah to guide us and you.
And Allaah knows best.