Praise be to Allah.
You should choose a wife who is religiously-committed and of good character, who will look after her husband and house, and raise her children well, and play her part in establishing a Muslim family and a Muslim society. This is what the Prophet (peace and blessings of Allaah be upon him) taught when he said: “Women may be married for four things: their wealth, their lineage, their beauty and their religious commitment. Choose the one who is religiously-committed, may your hands be rubbed with dust (i.e., may you prosper).”
You should not be careless with regard to this matter, or be swayed by emotion or so-called love. How many marriages have ended in failure because they were not based on the principle of choosing a wife who is religiously-committed?
No one will be punished for the sins of another, and he will not bear any burden but his own, as Allaah says (interpretation of the meaning):
“No one laden with burdens can bear another’s burden”
But a man cannot avoid interacting with his in-laws or visiting them, or avoid his children being influenced by them. Hence choosing a good and religiously-committed family with a good reputation is something that has a good effect on the husband and his family and children, and it is one of the factors of family stability and success in solving whatever problem may arise in the future, which all families are prone to facing.
Hence we do not blame your family for rejecting ties with a man who is a drunkard and has a bad reputation, because this will adversely affect them and their grandchildren.
Claims of love and emotion should be dealt with in a rational, fair and broad-minded manner. A man may imagine that he cannot do without this girl, and he cannot live without her, and that she has certain qualities and characteristics, but if he were to think about it rationally, he would realize how his emotions are over-exaggerated. Hence you must examine the situation closely and weight up this girl’s good points and bad points, and the pros and cons of marrying her, then base your decision on what you think most likely after weighing up the situation, without deceiving yourself, for no one is going to bear the consequences of this choice more than you.
If you do decide to go ahead and marry this girl, then try to convince your family and get their support, because the basic principle is that it is obligatory to obey one's parents if they forbid marriage to a certain girl, because honouring them is obligatory and marriage to a certain girl is not obligatory, and no exception is made concerning that except cases where a person fears he may fall into zina, if he thinks it most likely that not marrying a particular girl will lead to him committing haraam actions with her.
The family should not object to their son’s marriage if it is clear that he is attached to a particular girl, so long as the girl is suitable and righteous, because marriage is the best remedy for them, as the Prophet (peace and blessings of Allaah be upon him) said: “There is nothing like marriage for two who love one another.” Narrated by Ibn Majaah (1847) and classed as saheeh by al-Buwaysiri and by al-Albaani in al-Silsilah al-Saheehah (624).
If they develop the intention of being kind to the girl and saving her from her family, that is good, especially if you are going to move somewhere far away from them, and the children will not be affected by living in a corrupt atmosphere, then that will make it more acceptable to marry her.
It is obvious that you are a stranger (non-mahram) to this girl, and it is not permissible for you to be alone with her, shake hands with her, look at her beauty or talk to her about love and so on. If any of these things have happened in the past, then you must repent to Allaah from that, and you must repent from studying in the mixed environment which is usually not free from haraam things, and has bad effects on both boys and girls.
We advise you to consult good people whom you trust who know this girl and her family, and to pray istikhaarah and ask Allaah for guidance before taking any further step, because the one who prays istikhaarah will not be disappointed and the one who consults others will not regret it.
We ask Allaah to guide you and to make you take the right decision that will bring good consequences.
And Allaah knows best.