My partner and I are like this. We've been together for 14 years and are legit best friends.
I have a feeling too many people paired off right away and decided their first serious relationship was the one, and never actually found an equal. Maybe they married more out of fear of being alone rather than actual desire, or they just can't tell the difference between sexual novelty and love.
Even a lot of my married friends start identifying more with boomer humor than romance after 2 or 3 years. Way too many communication issue, or ideas of traditional roles or how things 'should be' leading to resentment or exasperation.
Court long and marry late. And don't hide your real self when dating.
I dunno. Dating long can bring its own gigantic bag of issues. You will have to build every relationship from the start. If you have a bag of expectations, fears, maybe even hard trauma that you project onto the relationship early on, it will make it more difficult to build the relationship.
"Oh my god he is not answering the phone. He is probably cheating on me right now how ex#3 did."
"She said she loves me after only week three of us having a thing. This is just like crazy ex#5."
"He didn't say he loves me after its been four weeks already. He is probably only affectionate now but will turn cold and distant like ex#4."
But those are all personality traits you need to discover and address before you're married. If you're the one bringing those concerns, you need to get yourself in check before jumping into long term relationships.