Imo Harem is when everyone okay with mc fooling around with other LIs and no hard feeling yet there couple of issues for example Emily case,fwb is fine tbh just y'know it would be good if there are no consequences later onThere's no planned tags provided in the OP, so can't really say.
As to the harem, it really boils down to what you consider a harem. You can have a number of the LI's with a FWB status. There's no formalized commitment towards them just being with the MC, although they never talk about seeing other people that I've recall.
As for pregnancy i think it's good idea i mean not for all LIs but some LIs like Chloe,Lauren,Nora or other girls with Motherhood vibes I mean some girls like Aubrey obviously isn't mother materials