There are several reasons why Thompkins may have left the Stylistics in the 1980s.
1. Creative Differences: Thompkins may have felt that he was not creatively fulfilled in the group. The Stylistics were known for their smooth, romantic ballads, but Thompkins may have wanted to explore different musical styles.
2. Personal Issues: Thompkins may have been struggling with personal issues that affected his ability to perform with the group. This could include health problems, relationship issues, or substance abuse.
3. Financial Issues: The Stylistics were very successful in the 1970s, but their popularity declined in the 1980s. This could have led to financial problems, which may have caused tension within the group.
4. Group Dynamics: The Stylistics had a long and complicated history, with several lineup changes over the years. This could have led to personal conflicts or disagreements within the group, which may have made it difficult for Thompkins to stay.
5. Desire to Pursue a Solo Career: Thompkins may have simply wanted to pursue a solo career and have more control over his music and career path.
It is important to note that these are just some possible reasons why Russell Thompkins may have left the Stylistics in the 1980s. The exact reasons are known only to Thompkins himself.