Is it wrong to go on a walk with a male friend if you already have a boyfriend?Watch
In general though, what is your reason for going on a walk together? Seems a bit of a random activity.
Anyway, it should be ok with your boyfriend but if he is a jealous insecure type then that's a red flag right there.
It's more about how it's viewed. If you care then you wouldn't do your boyfriend like that.
You are only supposed to be going for a walk with your immediate household or alone, not with anyone else at all, even if you practice social distancing. Check the government guidelines. This is assuming you are in the UK.