His heat was indeed coming soon this month, and Arren had never taken any heat suppressants since being together with Spade. It wasn't necessary anymore, as he already had his alpha to spend his heats with.
Omega heats came three times a year and happened once every four months. He had his heat in January, so he would have his heat this month of May. It just so happened that this was also his birthday month, and Arren wasn't hoping for a big party; he'd never had one in years, much less in a situation like they were in.
They already spent their heat and rut with each other, but both came somehow unexpected, and Arren thought they might prepare more this time around. He was a dominant omega, so his heats were destined to be worse and longer than the normal omegas.