let on gen.

[archimedis]

Certain moments are absolutely tailor-made for certain things. This is your moment to make an announcement of love, extend or accept an apology or let on that you're interested.

from the horoscope , I wonder indeed whether let on means here to pretend to be interested
or to betray an interest

[гарпия]

to be interested, show interest

[гарпия]

to be interested это я не то написала
to show interest - показать, что вы заинтересованы, а не скрывать это