It is ex-girlfriends / ex-wives plus heoine fisaco everywhere.
One other thing i noticed is that it is always the heroine is second choice / option to heros
Why can't the heroines the first love to heros ?
But very few shows tagged as love triangles in first place and that means the third person or rather the head ache is going to be there forever otherwise at least we expects the track of third angle may ends and focus only on two leads.