Ok, first things first, the only reason you need to end a relationship is that you don't want to be in it anymore.
A ten month old will adapt to having her parents live separately. She won't remember you ever lived together.
I don't think people are asking you questions to make you stay if you don't want to. They are just trying to understand what happened.
Four ideas spring to my mind.
The first is that he is anxious or depressed from lockdown, working from home, not seeing people or from becoming a dad. But you have batted that one back hard.
The second is that he has become controlling or verbally abusive- a not unusual change during pregnancy after birth of a child. But you haven't given specific examples that point this way just a change and perhaps moodiness if you feel he'd be happier without you.
The third is that because he traveled a lot before you just didn't really spend a lot of time with him before and now that you have gotten to know what general life living together without the excitement created by "wow you are back" and needing to make the most of one another before "sorry you are leaving", you are just finding it all a bit dull and flat and maybe you weren't long enough in his company before to realise you found it dull.
The fourth is, you have seen someone else who you realise you fancy more than your husband and the grass is greener and suddenly he looks dull by comparison.
Or fifth I suppose, which is you are still in the first year of your first born's life and you are finding the monotony of meeting a babies' needs, perhaps not getting a lot of support from your partner and are resenting him for it?
But maybe all of that is wrong. Do you just need a bit of space? Could you arrange a little weekend away for yourself and baby with a friend or relative and see how you feel?