The sooner you come to grips with it, the better.
Almost everyone has an agenda (a.k.a. Motives), of some kind, and their agenda is rarely the exact same as yours.
Sure, you might basically desire the same end results or be on the same team with a unified goal but you’ll likely have different perspectives on how to get there or what you want to accomplish along the way.
It doesn’t mean someone else’s agenda is bad or that they are simply using you to accomplish something of their own, it just means you need to be clear with each other on wants, desires and expectations so that full disclosure exists and no one gets upset.
It also means you need to look for ways to serve them and their agenda instead of only expecting them to serve you and yours.
It’s easy to lead and dominate with ours while not looking for ways to pour into theirs.
Don’t fall into that trap because if/when you do, the relationship gets one-sided and that is when resentment and undermining come into play.
If you don’t want them to use you to simply accomplish their agenda, don’t do the same to them. It goes both ways.
For me, I’ve always found it best to be open and honest with others by encouraging them to be the same. My agenda is mine and theirs is theirs. When it’s all on the table we can serve each other and help each other mutually.
That always seems to be a better way.