As far as the relationship thing... If you have healthy relationships with spouse/bf/gf or family there may be some compromises, but one side will not expect the other to not do what they love to do, especially if it is a healthy safe activity like bicycling. I'd suggest that if going on a bike tour will end a relationship, it probably either isn't a healthy relationship to start with or there are other bigger problems with it.
That said, family and friends may worry about you. You should do your best to allay those worries by explaining how safe the trip is and by trying to stay in touch with loved ones at home with some frequency when on tour. And yes bicycle touring really is pretty safe. The biggest risk is almost certainly vehicular accidents which in my experience are actually more likely when riding around town at home than when out on the mostly open road on tour.