but it's usually a lot weaker)
Depends what kind of nalewka it is...
the options on the alcohol
A man in his 20' would go for vodka, if contemporary anything really depending on his story and background. If you have something stereotypical in mind it could be a drink like zubrowka with an apple juice.
If a dress - doskonale, doskonala or swietnie, Not doskonaly.
Instead of fajnie - dobrze, dobra.
moja jedyna rather than jedyna moja it sounds like he is mocking her or is not quite serious. If that is some life and dead situation he would use her name rather than some endearing substitute.
kochanie, sloneczko, mala, zlotko, serduszko...thing is I'm not that young so that could be outdated too but it is still better than that cheesy bit from 40 years ago or more. lol