We need developer's cheats in order to edit relations between sims. First of all open the cheat window by pressing:
then activate the cheat:
after these steps, you can insert some cheat to edit your sims relations:
modifyrelationship <yoursimFirst> <yoursimLast> <targetsimFirst> <targetsimLast> <(-)amount> <track> - this edit relation level between sim, you need to replace:
<yoursimFirst> active sim name.
<yoursimLast> active sim lastname.
<targetsimFirst> target sim name.
<targetsimLast> target sim lastname.
<(-)amount> a number (positive or negative) between 1-100.
<track> choose between Friendship_Main / Romance_Main
modifyrelationship Daniela Alberghini Maurizio Alberghini 80 Romance_main
relationships.create_friends_for_sim - this cheat spawn a friend in your sim lot (at 50% friendship level)