Perfect tenses are used when you can still feel the effect now. The love is still felt and connected to the present, so the present perfect tense can be used, such as
Macau people have loved China since the 123 incident.
The word "since" is associated with perfect tenses, and can be followed by a noun, i.e. the 123 incident.
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Another example: Wendy has lost some of her motor functions since her stroke in September last year.
Here Wendy's loss of movement still affects her life right now. Again, "the stroke" is the noun following the word "since".