How to know if he's falling out of love?

The problem is he's becoming too comfortable in this relationship, meaning he knows you'll be around so he has more than likely given up on "trying". He just doesn't try anymore because it's almost like...routine. It's comfortable and he feels like he doesn't have to do anything anymore. Talk to him more about it, and tell him it's really upsetting you because you feel like you don't mean anything to him anymore. He's acting distant. Tell him that. Tell him it is really causing you to doubt how much he loves you these days. Maybe that will cause the fire to start under his *** and get him to do his part in the relationship, for fear of losing you..but you need to make it very clear that the way he's acting can't continue or else you won't be happy.