 If you liked
Koroshi Ai
|
 ...then you might like
Spy x Family
|
both have a similar theme, spy x family being family, and love to kills being... well love. Both have action pact scenes. I would say that Love to kill focuses more in the action rather than the theme tho.
Both are about spies or hitmen that have to stick together.
If you're coming from Spy x Family Koroshi Ai then imagine if Loid had a brighter personality and Yor had Loid's personality because that's exactly how it is in this manga.
If you're coming from Koroshi Ai to Spy x Family then imagine if Ryang-ha was the opposite personality-wise and Chateau was more optimistic and lively.