\documentclass{article}
\usepackage{wrapstuff}
\begin{document}
\begin{wrapstuff}
\fbox{XYZ XYZ XYZ}
\end{wrapstuff}
Some text normal. Some text which have \newline int it.
\begin{wrapstuff}
\fbox{XYZ XYZ XYZ}
\end{wrapstuff}
Some text normal. Some text which have \\ int it. Some text normal.
\end{document}
Text before "\newline" or "\" command disappear.