Long distance relationships can be scary for many people. They are filled with trust, vulnerability, and faith. For some, it's too much to deal with... and if those people are your friends, they can end up projecting their own concerns on your situation. Tell them to back off. You're an adult and are doing love the way you see fit. In truth, if you have people filling your head with insecurities, it will end up seeping in to your thoughts. Get rid of all that negativity.