Caught him lying about his job

I've been dating my boyfriend (34M) for a year, and he always said he was a software engineer. Last week, I unexpectedly saw him working as a clerk in a grocery store. I feel betrayed and confused about why he'd lie. We have a great relationship otherwise, but this deception makes me question everything. How should I approach this conversation? Any advice? #WhatWouldYouDo #TrustIssues #RelationshipAdvice