ADVICE PLEASE!!!! Should I break up w/ him?

Before dating my boyfriend, I was pretty good friends with his ex. She was the type that talked about everything in their relationship with anyone who would listen. They had lots of problems and just didn't really work together, but one of the things that she told me was that he stopped trying and wasn't really there anymore.

When he and I started dating I told myself that if I noticed the same patterns I would end it to save myself some heartache.

The last few weeks I've noticed some changes. He doesn't text as much and doesn't get as excited to see me. We're long distance and he used to get so excited when I would come home, but lately he doesn't really seem to care.

He still tells me he loves me and he talks about our future, wanting to get married when we're done with school, etc.

Do I stay true to the promise I made myself and end it? Or am I reading too much into this because I've been watching for it? Should I give it time or bring it up asap? Am I being too expectant?

Please please help me!!!!