If you are searching for some universal argument that shows existence is meaningful, well then you are probably out of luck. Nobody is able to deduce out of thin air that existence is meaningful. This is simply because you can’t deduce anything without assuming something. However, if you feel that there are things in live that are meaningful, then it isn’t difficult to deduce that there is meaning to existence. Again, there is no universal argument to show that for example love is meaningful. But if you strongly feel that it is, then it is justified to declare that it is so in every sense of the word. Axioms of mathematics aren’t really any different: one just chooses them to match intuition.

Of course, if you really can’t find any sensation of meaning or importance from anything at all, then it becomes really difficult to find a meaning for existence in any sense. But you said that you don’t want to keep hurting your boy friend. So perhaps you can still find some importance from the people closest to you.