Swift-mania's in overdrive ... but Taylor's ex Joe Alwyn looks like he's feeling the total opposite, 'cause he's popped up for the first time since her engagement news, rocking an outfit as blue as his mood.
TMZ got the shots ... the Brit hit the London streets Wednesday with a buddy, but couldn’t muster even a hint of a grin ... a sharp contrast to his ex, who’s now riding high on engagement bliss.
Joe -- who called it quits with Taylor after 6 years together, months before she linked up with Travis in 2023 -- clearly looks down and out.