Shadowhunters- The Mortal Instruments - Season ... -

- main: synonyms could be primary, major, principal.

"Clary and Jace’s" is kept as is, since those are names. SHADOWHUNTERS- The Mortal Instruments - Season ...

Let me break down the first sentence: "Meanwhile, Clary and Jace’s relationship is put to the test as they face obstacles and secrets that threaten to tear them apart." - main: synonyms could be primary, major, principal

"American" → US (though "US" is repeated, maybe the user wants synonyms) - main: synonyms could be primary

"third season" → season three (though "season three" is correct, "next season" might not fit here as it's the third one)

"obstacles" is barriers

"television" → TV