Something that buyers and sellers appear to often be unaware of is that their contractual obligations are not to their agent, but to that agent's broker. Which is why you want to ensure that the broker doesn't come after you for payment.
The manner in which you handle this with "your friend" is up to you.
I'm not certain if you're achieving the goals you set for yourself when you began this process two years ago, but your story doesn't appear to be a ringing endorsement of going "Buying By Buyer."
Talk to your friend and explain your situation and get everything out in the open so that there is no confusion after the fact.
1. Full time professional
2. More experience
3. At your beck and call 24/7
If your friend agent can't do that and that is what you require, there is no reason for them to fight to keep you as a client. You are a mismatch. If they are any sort of professional at all, they will refer you to another agent within their firm, a full time professional. If you close a deal using another agent they've referred you to, they usually get 20% of the selling office commission. Usually this salves the wound a bit and you can probably go on and be friends as if nothing happened.
I think there is less chance of your agent/friend or the brokerage firm trying to get you to pay a brokerage commission or claimng "procuring cause".