\documentclass{article}

\usepackage{mathtools,eqparbox}

\begin{document}

$
 abc
 \rlap{\eqmakebox[arrow]{$\xRightarrow{\phantom{abc-def}}$}}
 \eqmakebox[arrow]{$\genfrac{}{}{0pt}{1}{\strut abc-def}{\strut def-abc}$}
 def
$

\end{document}