Per Zoe’s lines, Ezreal and Lux are together.
Taric loves (and protec) all life, I don't think he would be even considering a relationship and would just be kind of enjoyable flirting (not in a kinky way, just really suave) with everything he considers beautiful.
Also I don't see him meeting with Ezreal any time soon. Other Targonians and Kai'Sa have far more chances at meeting him.
I support the theory that Ezreal is just Lux in disguise. The 'crush' Ez has for Lux is just Lux's wishful thinking to have a bishonen anime protagonist boyfriend.