To be honest, i dislike romance in stories. They are usually badly written. But I will avoid this topic.
Any stories with a harem tag put me off. The characters seem fake and stupid every time they are involved in it. The members of a harem often lose parts of them once put in it. Some seem so out of character that I wanted to puke.
Obviously, if the author had put time and effort into creating a good harem, I will praise it. But there are just too few to speak of.
TL;DR. Don't write harems unless you are very good at writing romance.