I'm a speech pathologist, and I work with adults who have communication disorders. One thing I love to work on in therapy with my patients is their ability to say "I love you!" to their spouse/kids/grandkids/etc. I believe that expression of emotion provides so much healing to the situation for both parties.
My son, Jack, has autism. He was diagnosed at 2, but I knew in my heart before that. Around 3 years of age we raised money to purchase an iPad and communication app that I could program to fit his needs. Our hopes were to replace some of his screams with words. The first time he was able to tell me "I love you!" was the first night we worked with the iPad. I will never forget that moment and the healing it began in my heart. Through repeated use of that device Jack started to copy the words and phrases as he touched the buttons. He was also in intensive therapy. Later on we had the opportunity to go to Disney World as a family (those credit card points add up when paying for loads of therapy, and we wanted to do something fun as a family with that - we needed a pause from life!) While we were there something "clicked" with Jack. When we returned home he became fascinated with Disney movies and especially enjoyed watching the "happy endings" over and over. It was during that time that I received my first kiss from Jack. He started requesting "princess kisses" from me (sure to melt any Mama's heart).
Jack is almost 6 now. He tells me he loves me, and he accepts kisses on the cheek. When watching movies (The Little Mermaid especially) he pauses them exactly on the moment of the kiss at the end and asks Mama for a "princess kiss" to "make a match". It doesn't matter what we went through that day, it melts away when I feel that love.
(Pictured above: Jack and I headed out to see The Little Mermaid play in our town. He loves Ursula, and he quoted all her lines and clapped upon each appearance on the stage. At the end of the play Ariel kissed the prince and Jack grabbed my face for a princess kiss!)