Himari got possessive in a cute way, I guess? He doesn't understand it himself. But that soft look on Gaku's face when Himari asked if they could hang out in his room...
http://www.mangago.zone/read-manga/golden_sparkle/
Momo's pettiness was cute when Kuri and Yata were talking together. Yata's pretty clumsy when it comes to his own possessiveness but he's a good guy. HEAVY themes though.
http://www.mangago.zone/read-manga/yatamomo/
Sawahata definitely wants Hoshizaki for himself. It's amusing to see the thought of an almost yandere but Hoshizaki sees through his thoughts.
http://www.mangago.zone/read-manga/shitteru_yo/
Not sure if possessiveness or just jealousy (squint.jpg)
http://www.mangago.zone/read-manga/soredemo_yasashii_koi_o_suru/
http://www.mangago.zone/read-manga/ore_no_itoshi_no_neet_kun/
Any yaoi that has a possessive character? Not possessive as in "grrr you can't talk to anybody and I'll control every aspect of your life because I see you as my posession" but posessive as in "you belong to me and i don't want anybody else seeing how pretty you look in bed" and the such.
Basically, non-abusive possessiveness. I hope I sound reasonable haha