I'm not very chatty, DP is the complete opposite
I'm not a naturally conversational person, I take too long to consider my response before saying it, so in a group situation someone else jumps in before I've started talking, and the conversation moves on.
I'm better one on one, but with a very chatty person or someone who hates any form of silence in a conversation (even just a second or so), I still struggle a bit.
I'm much better when messaging, because there's a natural back and forth, and no-one cares if there's a bit of a delay before getting a reply.
I'm also much better when I'm a bit tipsy. It short circuits the bit of my brain that's sat in the middle of thought -> speech, so I become quite the conversationalist.
With DP, we were both steaming when we met in a club, and there wasn't a lot of talking going on initially. When we first started going out on dates then, I'm sure she must have initially thought I was really dull until we got a couple of drinks in.
It didn't really become a problem until we started just hanging out round each others houses etc. when DP started having the same sort of concerns you've got @Imaysnapandfart .
We learnt to adapt to each others conversational styles. I learnt to just let DP do her stream-of-consciousness thing without me getting frustrated that she wasn't leaving a conversational opening for me. She learnt that she didn't need to fill the slightest silence, because if she gave it a second I'd say something. I learnt to use body language to indicate I was about to speak, she learnt to keep an eye out for those cues.
It's mostly a subconscious practise, but you just learn to adapt to each others conversational styles over time.