I would actually say that it's deeper than a forced GF. The relationships between Jessie and Jack/mc is part of the story itself.
I didn't think about the cheating tag, I guess it would qualify. However cheating is a choice you can make and the risks are very apparent.
You can have 3 girls but I'm not sure if it's a harem in the way that it's mostly used in AVNs. 3 girlfriends is how I think of it.