He doesn't even greet me when he comes home in the evening

For the last two days, my spouse comes home and goes straight to their room without even properly greeting me, with a frown on their face. I asked if something was wrong, and they just said, ‘I’m tired,’ but this behavior isn’t normal. We’ve never experienced anything like this before; is there a problem at their workplace or something? Or are they hiding something from me? I just can’t understand.