Implicating liquefactiophilia → melting
Link to implication

Reason:

Liquefaction, in biology, is when organic tissue seemingly becomes a liquid. Liquefactiophilia is the love of liquefaction, and implies liquefaction.
Melting is when a solid seemingly undergoes a phase transition to a liquid.
Therefore: Not all melting is liquefaction. All liquefaction is melting.

An alternate course of action would be to let liquefactiophilia imply liquefaction and let liquefaction imply to melting.
However, there currently are no images tagged with "liquefaction", and I'm unconvinced that it would be a useful tag to add because it's closely linked with the already existing liquefactiophilia tag.
Here's an analogy. The oral_vore tag is closely related to the eating tag. Oral_vore implies that eating either has taken place or is taking place. Because tag what you see is a thing, oral_vore does not imply eating. However, in the case of liquefactiophilia, there is no such disconnect from liquefaction. Liquefaction has to still be taking place.
A third possibility, therefore, would be to alias liquefaction to liquefactiophilia (or the other way around), and imply liquefactiophilia to melting.
I remain unconvinced that liquefaction is a useful tag to have at all, though.

EDIT: The tag implication liquefactiophilia -> melting (forum #229108) has been rejected by @NotMeNotYou.

-1, probably alias it instead. Explanation bellow:

I) You are right, they aren't exactly the same process¹; however maintain those tags separated due such technicality isn't something practical.

II) OK, "philia" denotes that the tag is supposed to be used for cases in which a sexual/romantic/pleasurable² context is noticeable, however the majority of posts under 'melting' already fit in this (except melting objects and maybe some instances of digestion).

¹ Liquefaction: when a solid becomes a liquid (melting) or when it reaches a relativelly fluid consistence upon blending with a liquid (dissolving).

² Subjective, very subjective.

Alias makes sense as well. Either way, I feel like at least something has to happen to associate those tags.

The tag implication liquefactiophilia -> melting (forum #229108) has been rejected by @NotMeNotYou.