Possible Clues:

• Affectionate letters in American Sign Language
• Letters of affection
• "ur the best"
• 'ur the one 4 me'
• Sign of affection, in 28-Down
• 'Mwah xoxo'
• What '<3<3<3' might mean (Abbr.)
• Cheer's conclusion
• Might finish?
• Adverb ending