Define "Love"
Humans can feel attraction, attachment and lust for each other. Pokémon don't feel lust, so only the first two can appear. And that only happens with selected mons, the ones that have a "conscience". A wormple can't love you back.
However, attraction of pokemon towards humans works differently than for us.
The only thing that attracts pokemon are pheromones that signal fertility.
Pheromones are unique odors that are secreted by a pokemon to signal different states of mood like the need for sexual contact, fear, aggression, etc.
The reason why mons don’t feel sexual attraction toward humans is that humans secrete different kinds of pheromones that only turn on other humans specifically. We aren't in the same egg group.
So while it's definitely possible that a mon feels like you're its perfect match, and feels extremely attached to you for all its life, it will never feel sexually attracted to you unless you put on the right pokemon pheromones. You can buy them online. 10/10 would recommend
