Is the suitor obligated to marry the one with whom he committed preliminary acts of fornication, knowing that his engagement was annulled by his family due to their disapproval of her?

It is necessary to warn against the danger of being lenient in the interaction between a suitor and his fiancée, as they are considered strangers to each other until the legal marriage contract is concluded, and repentance from these forbidden acts is obligatory. If the parents' objection to marrying this girl has a legitimate reason, such as her being disobedient, then obedience to them is obligatory. Otherwise, obedience to them is not obligatory, and you are permitted to marry her.