This one was written by Toto guitarist/vocalist Steve Lukather. It's a power ballad, light on the power and heavy on the ballad. The song is about letting an old love go and promising not to stand in their way as they pursue a new life.
Toto IV was a huge album, featuring the continental hit "Africa." But "I Won't Hold You Back" was the only song from the set to top the Adult Contemporary chart, giving Toto their first #1 on that tally ("Africa made it only to #5).