 Gary Chapman and I, in our book, Building Love Together and Blended Families, talk about different love associations. The nature of different relationships, love means different things about different people. I love my mother-in-law, but it's not the same as how I love my mom. I love one sibling differently than I love another sibling. You loved your step-parents, but not in the sense like you love your biological parents, and so the words I love you just weren't appropriate.