Even in badly written Jap harems, even though the guy is the world champion of dense virgins, all the girls are romantically interested in him for some reason - and usually he is interested in one or more of them too from the start. So there is at least one-way romantic interest betweem him and each girl, making it a harem.
If it's 2 girls, it's either a love triangle or a menage a trois (mini-harem) depending on context
No, Its only a harem if the women are in love with the mc and the mc with the women (can just me woman love mc but nonetheless).
A harem is either romantic, or for political purposes.
Or, real world, a bit of both - some romantic ties going in, some that develop, but most of the pairings are due to politics.
I also forgot to mention, that what OP posted, isn't a harem. If he's only dating one, than no, it's not a harem. It's annoying how many people abuse and misuse the harem tag. I don't care how many people are fawning over one person, if they only reciprocate towards one, than it's not a harem.
A harem is only a harem if it is 3 or more. Three is the bare minimum.
By the traditional definition of harem, that is not a harem. However, as the Japanese use the word/genre, it can be considered one. Lots of their "harem" stories, like Rosario Vampire and Nisekoi, feature lots of girls going after a guy, but in the end he only picks one of them.
