What assurance does Ishi give to Timawi when Timawi observes that Tushi prefers Ishi's company?

Ishi assures Timawi that even though Tushi seems to prefer spending time with Ishi, he and Tushi could never be more than friends because they are cousins. The family ties are too close for them to have a romantic relationship. Because of this, the only logical partner for Tushi is Timawi.