OP.. are you in for long term relationships? or you just want to be in a relationship for sex? perhaps the "nice guys" want a girl who are more emotionally involved in the relationship and care? You did not mention your feelings at all, and seem somewhat detached, so it would be helpful if you share your view on this.. rather than just asking if you're normal for having all your exes dump you.
if you're bored.. instead of getting a new romantic relationship, perhaps you should just make friends instead... do you have any other friends? hanging out with them if you're bored?
if you just stay at home all the time + boyfriend, that seems very dull. and perhaps your bfs felt that way too.
and guys don't like it if you're too easy... and they move on.