We had up until Wednesday evening 2 mute swans, a male and a female

The female has gone missing from Thursday morning, we are really hoping it's because she is sitting on a nest.

However our other fear is that she has died, thus far I have been unable to find a body but our property is complicated and hard to travel without a canoe (Lake/Wetlands etc.)

He doesn't seem agressive but keeps calling out for her, or calling to her.

Is their anyway I can tell if he is greiving? Or anyway I can tell if his behaviour is due to a nesting period?

Thank you for your time in advance.