Is it permissible to celebrate annually a special day coinciding with the 15th of Ramadan as "the day of joy and love," and is it permissible to ask guests on this day to pray for God to unite them in goodness and happiness?

This relationship between you and a non-mahram girl is fundamentally an abomination, as it is impermissible for you to mix with her, be alone with her, or enjoy her conversation before marriage. Your celebration of Valentine's Day is an abomination, for everything built upon falsehood is false. Celebrating this holiday is a reprehensible innovation and an imitation of non-Muslims. Muslims have no holidays other than Eid al-Fitr, Eid al-Adha, and Jumu'ah (Friday). It is advised to expedite marriage if she is suitable to be a Muslim wife.