Ranma ½, Nisekoi Recommendations
Both are rom-coms where a boy and a girl are forced to be a couple by their fathers. Though the boy and the girl hate each other at first, after a while, hate starts to change into love. Both series have also other girls who have crush on the boy. Also, while Ranma ½ is ecchi, Nisekoi isn't.
Both harem, many waifus and the main waifu is a grumpy one. Both are about a marriage promise. Main boy searching his waifu among waifus.
Enjoyed the Harem , the male Protagonist in both the anime series experience a 4 girls around him who is directly or indirectly love him. But the male protagonist is too dense to feel it and even though he know didn't want to get involved in any of the relation!