The only thing that could be an issue there is signficant age difference (or setting-specific religious/cultural things). Nothing in the druid or cleric classes disallow marriage - though some druidic schools of thought or clerical callings might. That's a setting-specific thing, though.
One matter of concern is lifespan difference, though - the half-elf may outlive his wife by 50 years.
Both characters are in their 20s. So it should work. I don't see the campaign setting I've been playing go all the way to their natural death of old age. Thanks for awnsering and giving me some input.