He told his Hindu girlfriend that he would give up his religion; what should he do?
Question

                I live in uk and there was a hindu girl i was in love with and she forced me to say that i will convert and i said ya but it was like i just said in my heart i knew i wont and i never converted and on top of that i agreed to a few things that i shouldnt but just to keep her happy but not from my heart and now i think i have made a big mistake what do i need to do now?.
Praise be to Allah.
    What you have to do is repent 
    to Allah, may He be exalted, say the Shahaadatayn and come back to Islam, 
    because a person becomes a kaafir the moment he says that he will apostatise 
    in the future, or he decides to apostatise, or he says, “If such and such 
    happens, I will apostatise,” because adhering firmly to Islam is essential, 
    and any hesitation concerning that constitutes kufr. 

    An-Nawawi (may Allah have 
    mercy on him) said: Deciding to become a kaafir in the future constitutes 
    kufr in the present. Hesitancy about whether to commit kufr or not 
    constitutes kufr in the present, as does making it conditional upon some 
    future event, such as saying, “If my wealth is destroyed or if my child 
    dies, I will become a Jew or a Christian.”  And approval of kufr is kufr. If 
    a kaafir who wants to become Muslim asks him to prompt him to say the word 
    of Tawheed and he does not do that, or he indicates that he should not 
    become Muslim, or he suggests to a Muslim that he should apostatise, then he 
    is a kaafir.

    End quote from Rawdat at-Taalibeen, 
    10/65

     In al-Mawsoo‘ah al-Fiqhiyyah 
    (42/307) it says: The fuqaha’ are of the view that if a Muslim thinks of 
    becoming a kaafir, or he has doubts about the Oneness of Allah or 
    Prophethood or the Day of Resurrection, or he intended to stop being a 
    Muslim, or he is hesitant as to whether he should become a kaafir or not, or 
    he decides that he will become a kaafir tomorrow or in the future, he goes 
    out of Islam and becomes an apostate immediately, because developing doubts 
    contradicts the firm intention to be a Muslim. End quote. 

    It is not permissible for a 
    man to have a relationship with a non-mahram woman, and it is not 
    permissible for him to marry a Hindu woman unless she becomes Muslim. 

    You have seen for yourself 
    the consequences of this haraam relationship, which led you to speak words 
    of kufr. Beware and be very cautious of such relationships. Pray a great 
    deal for forgiveness (istighfaar) and do a lot of righteous deeds in the 
    hope that Allah may forgive you and accept your repentance. 

    And Allah knows best.