I do feel that ZWJ loves ZM as much as ZM loves him. Just that ZM is the more direct one, whereas ZWJ only shows through his actions, not words. He always cares for her in the tiniest of acts, and when no one else is around or when ZM doesn't know (e.g. the apples at Snake island, lending her the shoulder at the cave).
ZWJ is nicknamed "Zhang-Always-Break-Promise" because he never does what he says:
-"Girls and guys cannot touch each other" --> carry, grab shoulder, touch feet
-Promised he will kill ZM at the first glance --> spend the night in a cave
-After leaving the inn where XX disappeared "After tonight, I won't care about your death or alive" --> save her 100x times from his bros, family, fiancee, enemies, etc.
-After wedding "I wont be with you this whole life" --> the next time "i want to be with you this whole life"
The only promises he has successfully kept are showing her the Dragon Sabre, not marrying ZZR and getting her some friends at her tombstone