What is the permissible love in Islam, and is it permissible to communicate privately with an unmarried girl without sexual innuendos, or to express love to her? And do I have the right to marry her if my parents object?

Permissible love is that which enters the heart without intention or deliberate will to commit a forbidden act (such as looking or mixing). However, speaking or writing to a girl is not permissible if there is a fear of falling into the forbidden. It is advisable to abandon such love, even if it began innocently, lest it develop into falling into the forbidden. If the parents object to marrying her, then one must try to convince them; otherwise, the good may lie in seeking someone else.