Curate, connect, and discover
Mammon does in fact tattle to Lucifer about Asmodeus and Fizz's relationship. Let's say the Helluva timeline lines up with Lucifer and Alastor getting closer sometime after season 1.
Lucifer doesn't know why Mammon bothered, even if Lucifer didn't have whatever was going on between him and Al -- he still wouldn't give a fuck. And he'd give even less of a fuck considering Mammon was still committing copyright infringement for his park, the audacity of that man was astronomical.
Still, Mammon calls a meeting to spill the tea because even he knows Lucifer is a hermit who does not keep up with the drama of Hell's so-called elite.
Asmosdeus finds out and therefore Blitzø finds out. So they all crash the meeting to give Mammon what-for. Fizz and Blitzø because they've never met Lucifer and think he's going to be pissed. Moxxie and Millie because Blitzø lied about where they were going and refused to let them leave. Stolas for moral support (and he's also never met the King, sue him, he's excited despite the circumstance) and Ozzie because he couldn't stop them so he might as well join them.
Following multiple very unnecessary pit-stops and shenanigans, they finally arrive at the palace---and it's too late.
Alastor has already kicked Mammon out and now he and Lucifer are doing paperwork, gossiping, and fighting over the (according to Alastor) tacky interior design of the palace.
The Helluva gang bust in (Blitzø is on a horse for some reason, he's very happy about this) and it's very anti-climatic.
Asmodeus: so you...don't care that I'm in love with an imp?
Lucifer, dad mode: You're in love? I'm so proud of you!
Blitzø: Just to be clear, I'm fucking this bird, there's nothing you can do about it
Lucifer: Okay??
Alastor: Darling, they think you care about hell's hierarchy
Lucifer: Oh! Yeah, uh-no. That'd be pretty hypocritical of me considering [gestures to Alastor]
The Helluva crew leave the palace once Lucifer and Alastor start bickering again looking like they've escaped a hurricane, wondering if they should be sending the King of Hell a 'Congratz on the Divorce' card.
Moxxie: ...does this mean we have two Kings now?