Like I said, I'll ship it. Even in the webnovel, where it's clear they only think of each other as best friends, the two of them still set off a whole bunch of romance flags with each other. Hell, they've each planned to dedicate their "first times" to each other (doesn't mean what you think it means, but I'm 99% certain that the suggestive implication in the phrasing was just as deliberate in japanese as in English).
Wait can you tell where you read it and what chapter please?
The novel can be read through novelupdates, here: https://www.novelupdates.com/series/itai-no-wa-iya-nanode-bogyo-ryoku-ni-kyokufuri-shitai-to-omoimasu/
As for which chapter I was referring to, I can't remember and I don't care to go digging at the moment. It was quite a while ago. The gist is that they both want the other to be the first person to defeat them, but the way it's first phrased, and the way Sally at least comes across as saving herself for Maple, it seemed clear to me that the author intended us to read the other implication into it.