Dought & clear, - What are the limits within which parents may interfere in their son’s marriage? Is he sinning if he goes against their wishes?.

I have got to know a girl who recently became Muslim (she was
Christian before) and we have agreed to get married, but my family are
strongly opposed to that.
Praise be to Allaah.
Firstly:
We hope that you will pay attention to the things you have done that
go against sharee'ah, such as getting to know that girl who is a
stranger (non-mahram) to you, talking to her, making friends with her
and other shortcomings to which you have admitted. You should
understand that these sins mean that you must give them up, regret
doing them and resolve not to do them again, as well as praying a
great deal for forgiveness and doing righteous deeds.
With regard to your relationship with this girl, it is not permissible
for you to talk to her or see her, let alone make friends with her and
be alone with her. It is good that you and she have thought of
marriage, because it is the only legitimate shar'i way that you can be
together, so do your best to attain that; but if that is not possible
for you, then this relationship should be ended completely and perhaps
Allaah will compensate you with someone better than her and will
compensate her with someone better than you.
We have discussed the issue of correspondence between the sexes being
haraam in the answer to question no. 26890and 10221.
With regard to haraam infatuation and its effects, and marriage to the
one with whom one is infatuated, please see the answer to question no.
47405.
Secondly:
With regard to your family's objections to this marriage, you should
note that the parents' relationship to their son's marriage may take
several forms, such as the following;
1-
Not approving of any girl whom he chooses for himself as a wife.
2-
Not approving of a girl whom he chooses, but their objection is for
legitimate shar'i reasons, such as if she has a bad reputation, or she
is not Muslim – even though marriage to a Christian or Jewish woman is
basically permissible.
3-
Not approving of a girl whom he chooses, but it is not for any
legitimate shar'i reason, rather it is for personal or worldly
reasons, such as if she is not beautiful or is not from a good family,
and he is not infatuated with her and he does not fear any harm to
himself if he does not marry her.
4-
The same scenario as that mentioned above, but he is infatuated with
her, and fears fitnah for himself if he does not marry her.
5-
Forcing him to marry a girl whom they choose for him, even if she is
religiously committed and of good character.
It seems to us from the rulings on the scenarios mentioned above that
the son should obey his parents in the second and third cases, and
that it is definitely obligatory for him to do so in the second case.
In the second case the matter is clear and he has to obey them,
because he is going to do something that is bad for their son and may
also affect them.
In the third case it is permissible for him, but obeying them is
obligatory, and what is obligatory takes precedence over what is
permissible.
As for the first, fourth and fifth scenarios, it does not seem that he
is obliged to obey them, because choosing a wife is the son's right,
not the parents'; they may intervene in some cases but not in all.
Preventing him from marrying any girl he chooses, regardless of
whether she is religiously-committed or not, is pointless and he does
not have to obey them.
The same applies if he is infatuated with a woman and fears fitnah if
he does not marry her. In this case he does not have to obey them if
they tell him to leave her and not marry her, because that may lead to
evil and fitnah that Islam came to prevent.
It is definite that he should not obey them in the fifth case, which
is where they force him to marry a girl whom they have chosen. This is
not a matter in which he is obliged to obey them. Rather it is akin to
food and drink: he may choose whatever he wants to eat and drink, and
they have no right to control that.
Ibn Muflih al-Hanbali (may Allaah have mercy on him) said:
The parents have no right to force their son to marry someone he does
not want. Shaykh Taqiy al-Deen (i.e., Ibn Taymiyah – may Allaah have
mercy on him) said: Neither of the parents has the right to force
their son to marry someone whom he does not want, and if he refuses
then he is not sinning by disobeying them, because no one has the
right to force him to eat food he finds off-putting when there is food
that he wants to eat, and marriage is like that and more so. Food that
one is forced to eat is unpleasant for a short while, but a forced
marriage lasts for a long time, and it harms a person and he cannot
leave it. End quote.
Al-Adaab al-Shar'iyyah(1/447)
Based on this, we say:
If that girl has embraced Islam and become a good Muslim, and you are
infatuated with her, and you fear fitnah if you leave her, then we
think that you should marry her, even if your mother does not agree.
That applies even more so if you fear that her religious commitment
may be affected if she has no one to look after her.
We advise you to try to convince your parents so that you can combine
two good things: obeying them and marrying the one with whom you are
infatuated. You can get married without your mother's knowledge, and
try to guide her and advise her, and say du'aa' for her and for your
father.
You should remember that because it is permissible for you to marry
whomever you want and you do not have to obey your parents (in this
matter), you should not fear their du'aa' against you or their being
angry with you, because that is a sinful du'aa' which Allaah will not
accept from them, in sha Allaah, unless you are wronging them and
transgressing against them. Because it is permissible for you to marry
without adhering to their wishes, you will not be sinning or doing
wrong.
See the answers to questions no. 82724and 84052.
See also 21831and 5512.
In those answers you will see more examples of that which we have
discussed above.
See also the answer to question no. 5053for a discussion on the rights
that your mother has over you, and your rights over your mother.
Thirdly:
You should remember that it is not permissible for you to marry this
girl without her having a wali (guardian). If she has a wali from
among her family who is Muslim, then he must agree to the marriage –
but a kaafir cannot be her guardian if she becomes Muslim. If there is
no Muslim among her guardians then a Muslim should act as her wali,
such as a shar'i judge (qaadi) or Mufti, or the imam of an Islamic
centre. Whatever the case, it is not permissible for her to get
married without a wali.
And Allaah knows best.