not in a way either anticipated...meryl is a very awkward combination of chatty/running her mouth but also very hard to pin down about her actual feelings. and milly is very forthright when she wants to be but also won't push someone-like how when vash puts his facade back up in the jail, she plays clueless. she's very good at acting clueless and making others think she's clueless.

getting together would happen after awhile of traveling and certainly doing things that feel adjacent to things you'd do in a relationship but without that label attached. it's interesting because with a lot of my ships i don't necessarily see them "asking" someone out or getting together in a traditional sense because they are under very unusual circumstances. also, even though meryl and milly get close i do think milly would have a period of time towards the beginning of their travels of not knowing if meryl is into women, or anyone at all for that matter LOL. it would take time for her to realize that meryl wasn't just being weird or flustered around her because she's easily worked up.

milly would think she might need to be the one to take the lead when meryl takes her by surprise again. probably when they have downtime at a hotel at the end of the night, meryl asks milly if she ever thought about traveling with someone else. like a man or someone. milly says not really, does meryl think of that sort of that thing? meryl says not really, but well, despite their life of traveling they're not getting any younger. a lot of people don't stay in this profession because of how there's no time to "settle down". milly comes from a big family she loves, meryl always assumed this was a temporary position for her.
meryl probably realizes due to her nerves giving her an extra edge of painful self awareness that she's prattling on, and that this is all a very long and drawn out way of saying that the thought of milly traveling with someone else feels very painful in a way she can't place but she's steeling herself for that eventual reality.
i think milly realizes this is the closest she's going to get to a confession from meryl LOL. and just says "well i have no intention of that because i like you and want to stay with you" which probably makes meryl short circuit from how instant and forthcoming milly is (not the first time.)

very saccharine yes i know but they really do feel like a romcom couple so something very sweet and cute seems fitting. takes a long time to happen but once it's talked about it's very instantaneous.