The Party's Over Lyrics
I never thought you'd stay
The love of laughter
My truth's no longer sane
Much older than you'd say
This friend of no-one
Time, creases on your face
I've been losing track
This crime of being uncertain
Of your love
Is all I'm guilty of
I never thought you'd stay
A style of reason
This life of masquerade
I've been losing track
This crime of being uncertain
Of your love
Is all I'm guilty of
Name the crime I'm guilty of
Too much hope I've seen as virtue
Name the crime I'm guilty of
To me this is about the breakdown point of a long-term relationship, likely a marriage, that the protagonist has been holding out for some time that the writing hasn't been on the wall for this relationship to completely collapse.
Looking deeper, it would seem that the protagonist has inevitably developed a love/hate relationship with their partner, complicated by varying factors like "...being uncertain of your love", how their partner seems to have no social circle outside of their family, is somewhat doubtful or in denial of the strength of the relationship themselves, and the most awkward (and a very common reason in real life) being the involvement of what is presumably their children for whom they've likely stuck together for the sake of, with an opportunity that hopefully at some point in the future the relationship can strengthen again - but it's now reached the point of no return in terms of separating and that neither have any need now to live "...this life of masquerade". As the title sums up, the party's over.
Overall it's probably the strongest song on Talk Talk's debut album and it's one of those songs that I wished that it had been recorded later around the time "The Colour Of Spring" was being made, where there would have been much less reliance on synths and could have had included a choir or some element of an orchestral feel, especially in the second half of the song when the tone changes.
[Edit: Additional bit.]