Really? Has Cheeky mentioned it somewhere that you can't end up with multiple ladies in the future? Otherwise I'll scrap the harem stuff from the post and the guide.
Cheeky has said nothing either way but no harem tag and many, many, many hints in game suggecting things aren't going to end well.
Katie and Jenna both kick off and dump MC if you admit to seeing them both this update. Sure you can hide it but it will come out eventually.
Katie is only willing to share with her friend, not her sister or mother, that she says multiple times.
Monica has warned the MC not to touch her daughters, she also doesn't share.
Jolina and Angel are looking for something more 1 on 1 as is Bella. Elaine I don't know anything about yet.
The only multi partner hint is for Katie, Deb and Lily. Plenty of warnings that nothing else is going to work out.
Carry on as you are, makes no difference really, just be warned for if/when it does go to shit.
If this was a harem it would make absolutely no sense to the story or the characters so unless Cheeky plans on changing everyone's personality then i'm not seeing it.