If someone who is trying to establish the 5 daily prayer but is struggling for example when they are at work and they get very busy they miss it but them make it up. but most of the time they pray at work. but they really want to change are they considered to be a kaffir and you should not marry them ect. I take the opinion that someone who abandons prayer is a kaffir but what are the opinions and evidence about the one who is trying to change and establish prayer. I have a proposal from a brother like this who my family know quite well. He is a good character but struggling regarding this but wants to marry someone who can help him be a better muslim and encourage and help him in his deen.
Praise be to Allah
The one who does not pray at all is a kaafir according to the correct scholarly opinion. See question no. 5208.
As for the one who prays sometimes and not at other times, some of the scholars are of the view that he is also a kaafir. This view was narrated from a number of the Sahaabah, and fatwas to this effect have been issued by the Standing Committee for Issuing Fatwas, foremost among whom was Shaykh Abd al-Azeez ibn Baaz (may Allah have mercy on him).
Others are of the view that he is not to be regarded as a kaafir unless he does not pray at all; these scholars include Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) and Shaykh Ibn Uthaymeen (may Allah have mercy on him).
See question no. 52923 and 83165
Work is not an excuse for delaying prayer until the time for it has ended, because prayer only takes a few minutes.
If the one who wants to propose to you delays some of the prayers, we do not advise you to marry him, because he is a kaafir according to some of the scholars, and he is an evildoer who is committing a grave major sin according to others.
Allah, may He be exalted, says (interpretation of the meaning):
Then, there has succeeded them a posterity who have given up As-Salat (the prayers) (i.e. made their Salat (prayers) to be lost, either by not offering them or by not offering them perfectly or by not offering them in their proper fixed times, etc.) and have followed lusts. So they will be thrown in Hell
Ibn Masood (may Allah be pleased with him) said concerning al-ghayy (translated above as Hell): It is a valley in Hell, very deep and with a foul taste.
If he announces that he has repented and has resolved to offer the prayers on time, and you think that he is righteous in other aspects, then there is nothing wrong with marrying him.
And Allah knows best.