It's not a conclusive ending, but it definitely wraps up more then you guys are giving it credit for, imo.
Since a magical girl's power comes from love, the fact that bff was able to beat the monster easily after it beat the mc's ass implies that he loves the mc even more than what we've seen so far.
He's also clearly lying and nervous about it at the end, as has been pointed out, so I think it's safe to say that they're mutually in love and that this is an implied eventual happy ending.
I would have liked closure on whether or not the mc was a girl/would end up staying that way, which seemed to be implied as it went on, or if it was just that being a girl forced him to confront the fact that he likes guys, but I'm fine with something like this just reaching a stopping point and I'm not bothered by the note it left us on, personally