Does ghastly love tanith

If you are referring to the Skulduggery Pleasant series by Derek Landy then yes, he does :)

If you haven't read either Mortal Coil and/or Death Bringer then these are spoilers, but Tanith gets taken over by a remnant, right after he asks her out and they kiss :( So sad ending for Ghastly.

But to answer your question, yes, he does :)