I am not gay, I am straight, so I will never have to deal with this discrimination. But as an ally, I would say that even though it sucks, I would consider a lot where to go. Very religious or old-fashioned countries, such as Tunisia or a lot of Southern American countries are probably not a good idea. If you want to go to one of those countries, you should probably hire an apartment or book a room in a private/remote resort. The staff are usually cool about it, you bring them their paycheck after all, but I have friends who have had unpleasant experiences with service workers (cleaners, drivers etc.) and with random people in the street. All in all, you shouldn't let small-mindedness ruin your vacation, though. You are entitled to live your life and love who you want.

If you want a "safe" place to go, albeit expensive, come to Scandinavia. I'm Norwegian and no one lifts an eyebrow if same-sex couples hold hands or show other public signs of affection in the street (except for maybe full-on make-out sessions, but that also goes for different-sex couples, so that's more a general thing). Europe in general is probably good, at least as long as you avoid Eastern Europe, they are the least gay friendly in Europe (no offense intended to anyone).