Families threatening for doing love marriage

Ask them to lodge complaint before police for life protection with the support of local lawyers

I agree with the expert advise of Mr. Sankarnarayanan.

You can also file a criminal writ petition before High Court.

It is better to consult and engage a local prudent lawyer for appreciation of facts, professional guidance and necessary proceeding.

As was advised seeking police protection by filing a written complaint is a simple way, as the Police may call the relevant persons and give counseling and even obtain binding letters.  No amount of protection is sufficient and no one can guarantee personal security,, one must take care of his personal safety.

Hello, Greetings of the day!
For the query you posted, I would suggest that:
First, try to settle amicably but if in case matters are in the stage where legal action is needed; 
Then, lodge a complaint in the nearest Police station and in the complaint mention or record the statements about the emotional threat or life threat (if any) given by the family for breaking the marriage. 
Also, you have an option to go for the Alternate Dispute Resolution like Mediation where parties in dispute discuss their concern with the assistance of a trained impartial third person who helps them in reaching a settlement.

Hope it helps
Regards,
Sneha Jaiswal
 

Two adults who have married against their parents  consent or willingness can still be considered as legally wedded couple.

If they apprehend threats from their parents or any other sources they can very well approach police seeking protection.

If the police is not cooperating or ineffective they can approach high court with a writ petition seeking direction to police after exhausting the same remedy available before the  judicial magistrate court.