Communicate (he might feel the same) as to how you can both reconnect.

Yes, maybe you are out of love with him. But maybe you (both) are not actively working on the relationship so as to keep the flame alive: date nights, have fun and/or travel together, regular frank discussions of 'where are we at', 'what your needs are' and 'what my needs are' etc.

If you let life take over then yes, a relationship can become stale and routine.