The item "Philter of Love"(DMG, p. 184) hast the following description:
The next time you see a creature within 10 minutes after drinking this philter, you become charmed by that creature for 1 hour. If the creature is of a species and gender you are normally attracted to, you regard it as your true love while you are charmed.
If the creature who was the first to be seen by the creature drinking the potion charmed the drinker, would the drinker continue to regard them as their true love while they are charmed? There's no distinction that you must be charmed "in this manner" or by the effects of the potion.
So, would charming a creature affected by the Philter of Love extend the potion's love effects for the duration of the charm?