Hi there! Be sure to reword this so your education system doesn't attack you for copying something from Brainly.
Let's break it down. A word we sometimes use is "sincere"
What does this mean? It could mean with empathy, or true feelings. It just means the person really means what they're saying.
"As she told me she loved me, with the pure sincerity in her voice, I now knew she was the one for me."
Have a great day!