I've run across the "if you loved me you wouldn't spend time with anyone else" person.
This was before I learned about polyamoury so I didn't have a problem, mentally, giving him my all. He didn't present this way in the beginning, unfortunately. He turned out to be a real thorn in my side though and I eventually left him for a better life!
There are as many ways to do polyamory as there are people practicing it!