second domain do not want to go to https

Hi

Currently it already happen for long time.
I'm using wpmu and have several domain.
web server is nginx

let say
maindomain.com
main1.com

i config to force ssl for admin and login at wp-config.php
maindomain.com is a main site and than put main1.com and main2.com for extra domain that i can choice if create a new site.
and then i make http://www.main1.com as a new site
i can go to https://www.main1.com/wp-admin/
and it's working fine.

sometimes after i updating multi-domain and domain mapping, it do not go to https anymore, a browser will give me a warning about looping.

and than i mark force ssl at wp-config.php and it work.
i see that http://www.main1.com will go to http event i put https at a front.
loop will be happen because of it go to https than http and loop there.

note: i never change any config.

i also want to create a main site for main1.com to have a site without www.
right now i create a new site under main1.com to have http://www.main1.com site
how to make it ?

regards,