As a result (stop me if this sounds familiar), Gramm released a solo album in 1987 (Ready or Not). The LP peaked at #27 and the single "Midnight Blue" broke the top 10. While Gramm returned to Foreigner to work on their next album (Inside Information), the writing was on the wall, and Gramm left Foreigner after his second solo album came out, 1989's Long Hard Look. (To be fair, Gramm did rejoin the band in the 1990s, but the second iteration did not have much success).
Long Hard Look yielded two top 40 hits, "True Blue Love" (which peaked at #40) and "Just Between You and Me," which hit #6. "Just Between You and Me" was co-written by the superb hired-gun songwriter Holly Knight (there is more on her on the post for John Waite's "Change," which she also co-wrote.) The nicely done black and white video intersperses Gramm with a nice young couple who seem to be acting out the song's lyrics.
Gramm would go on to have a major health scare (a benign brain tumor) in 1997; while he survived, the resulting treatment impacted his weight and voice. However, he seems to be doing well, and continues to perform.
By the way, "Midnight Blue" was posted on ERV in May 2014.