Nothing pulls forward potential issues in a long term relationship or marriage like travel IMO. I say this after taking some Ls.
Your approaches to money, planning, leisure/what you do with "free" time, sex, get highlighted like crazy. Same flash points as a marriage. What went down the last few times I traveled w/ exes was a microcosm of the relationship.
Girl A
*Best parts of the trip were smashing multiple times a day; incredible sexual chemistry
*Could not get on the same page about activities - I wanted a good mix of being active, staying on schedule, and just chilling to get my money's worth; she was cooler lounging around; she spent hella time on the phone on her fam even though it could wait and we had places to be
*Roller coaster of great sex, arguments, make-up sex, and relationship on the brink
Girl B
*Completely on the same page in terms of mix of activities, planning, etc.
*Stable, respectful, good communication
*Lacked sexual spontaneity because she was focused on logistics, anxious about some things, etc.
The 1st time traveling with both was ~ a year into what would be 3+ year relationships undone by the problems seen traveling.