Is he afraid that’s they aren’t a gated partner?

I think he is afraid that they aren't, like matsu might have an omega fated pair??

I think is more like, Yuuki hopes to have a family and grow old with Matsu-san, but since he's a beta and Matsu an alpha, my guess is that he fears their relationship wont last long cuz Matsu has a fated omega somewhere out there

Wait!! Tiki is Beta??????? I thought he’s an Omega!!!!

Yes that's what I think too, coz' he had witnessed an alpha-omega fated pair which is masaki and his husband (forgot his name

Yes he is a betaaa!