Croatia is still a country where homosexuality is taboo and frowned upon by some of the population. Without going so far as to say that it's dangerous or problematic to be homosexual in Croatia, it's advisable, all the same, to be discreet in your actions, words and general behaviour. If you're homosexual or travelling with homosexual friends, a trip to Croatia unfortunately has to be made with some precautions.
Cities such as Zagreb, or other places along the coast, have gay-friendly spots but it's better to remain discreet in the rest of the country. Amnesty International has investigated the intolerance of gays and lesbians in the country and found that verbal, and even physical, attacks can occur. So, without crossing this beautiful destination off your list, simply adopt neutral behaviour in public and keep signs of affection for private moments. Kissing or holding hands can still be shocking for some people, as well as openly declaring your sexual orientation in front of strangers.
There are specialist places which welcome gays and lesbians where it will be easier for you to behave openly in public.
All the same, since 2002 there's been an organised Gay Pride in Zagreb and another in Split since 2011. That year, several attacks were reported and the event is always heavily controlled by police, who fear that things will get out of hand. In 2012 and 2013, everything took place without incident.