Drowning your not-yet-girlfriend to give her her first kiss is a galaxy-brained move that only a very useful lesbian could come up with.
Also, the vignette with Weixi's drunken mom seems to establish that Weixi's story about her parents being dead is a lie, which strengthens my speculation that she is the usurper emperor's daughter, because that's a fact she'd definitely want to hide from her cousin.