I have been speaking to a guy for marriage, and our parents met. He is religious and has good akhlaq. Then his mum suggested him to do istikhara. And it came out as negative. The sayed who did the istikhara told him to wait for something to change and do another istikhara. So after a while he went back and did another istekhara for the niyya of continuing to talk for marriage. This has now come out as negative again.

I had told him that from what I understood, istikhara is when you are unsure about a decision, and we were sure that we wanted to proceed in getting to know each other for marriage. But he went ahead and did istikhara.

He is now unsure of ending this. What would you advice.

Generally Speaking our great scholars do not advise to do istekhara for good deeds including marriage. Unless there’s a good reason to doubt the situation.
At this moment would you say there’s reasonable doubt about the akhlaq or faith or compatibility of the two of you for one another. If there is then I would suggest paying a significant amount of charity and do it again. If not pay the charity and go on with getting to know each other.