I appreciate that your message was about love. Goodness knows "K + S Fur ever" is better than "death to the cops" or something crude or vulgar. Having said that, may I make a few suggestions:
1. when writing on the house of an English teacher, please try to spell correctly, and use words (and) rather than symbols (+);
2. when writing a message expressing your love for someone, consider choosing a venue that you can easily revisit, rather than the front porch overhang on someone else's house;
3. again, when expressing your love for someone, particularly your eternal love, consider using a medium other than pencil;
4. don't write on my house.