Odd.
This is perfectly realistic!
Ever tried having two girlfriends/pets/slaves at the same time?
It's a huge amount of effort just to pay attention to and care for one person!
I would agree with you if there were only one or two potential mates in the story. However, is it realistic to have seven amazing girls in love with you at the same time? Since we are not dealing with a realistic scenario, your point is moot. If this story allowed you to pursue individual girls without attracting all of the others at the same time, that would be a different situation, and I would definitely play that game. However, that would require a huge amount of additional content. The same is true if the author was to try to include enough well developed love alternatives for the girls you don't pursue. Since neither of these is a viable option, we are left with brokenhearted girls or a harem. Of these, I would chose a harem ending any day.
By the way, I find it rather disturbing that you use the term "girlfriends/pets/slaves" while talking about a story you call realistic.