They can still be together is Rin and Taiga form a bond. Cuz then Omega with be paired with and Alpha on both sides. But if lets say Kaoru were to break the bond with Yuka to form a bond with Rin, then Taiga and Yuka would be forever alone (Taiga could sill pair with someone else but never with his fated omega)... Well if Kaoru never met Rin, theres a high possibility that Taiga would've never bitten Rin (if we assume that he will bite Rin; because he said he was interested in his fated pair only. In other words, he realized that Yuka was his pair, and that he would never have him). To be honest, altho Taiga acted like a dick, I pity him. He does deserve love, everyone deserves a chance to change.
SIGHHHH... MAN I WAS ACTUALLY SAD. I THOUGHT RIN AND TAIGA WILL BE TOGETHER AND YUKA AND KAORU WILL BE TOGETHER, BUT FATED PAIRS. REALLY?! (╯°Д °)╯╧╧