You can refer to two people as lovebirds when they are obviously very much in love.
[humorous]
Jack and his missis are as happy as two lovebirds now.
lovebirds in British English
(ˈlʌvbɜːdz)
plural noun
humorous
lovers
The lovebirds are in the garden.
Jack and his missis are as happy as two lovebirds now.
Examples of 'lovebirds' in a sentence
lovebirds
The lovebirds certainly look like they had a blast.
The Sun (2007)
The reunited lovebirds have their entire family around them as they tie the knot for the second time.
The Sun (2009)
Will the lovebirds be reunited?
The Sun (2015)
The store has introduced a new counter selling caged lovebirds, while other lovebirds with equally exotic plumage continue to flutter around the store.
Times, Sunday Times (2012)
In March the singer helped two lovebirds get engaged at a show in London.