Neo Angelique
or
Fushigi Yuugi (she has like a load of protectors lol)

Until Death Do Us Part

I'd also like to add:
Pretear
Rensou no Aria

thank you guys! I love all your recommendations and some I had read it ;D keep adding other manga 😉

Pretear<-- sound amazing 😮 thankyou

Ultimate Venus, by the mangaka who did the crossdressing classic Tenshi Ja Nai!!. Then there's Toraware no Minoue - by the mangaka of Vampire Knight - although it's not one of my personal favourites. Also, if you don't mind it being the other way around (girl protects guy, although there's a bit of the opposite too), there's Tokyo Crazy Paradise (must-read!) and Grand Sun.