How can I rekindle my bond with my cat?

My cat is 10 months old and since a neighbour's cat has come into our garden to visit, I have stroked it and watered/fed it, thinking it might be a stray. This other cat has also come into my home and eaten my own cats' food! - though I shoosh it away. Since this cat has encroached on and in my property and I've made a fuss of him, my own cat has distanced himself from me and now we're hardly in the same room (he goes to sleep upstairs) and when I try to stroke him he does tend to dodge me. Is he threatened by this new visitor cat or what?