Saul was upset that his son Jonathan had acted in David’s best interests.1 The fact that he accused Jonathan of siding with David also suggests that he considered Jonathan’s actions to be a clear demonstration of his allegiance.2 Instead of being loyal to Saul and his family, Jonathan was loyal to David.
30 Alors la colère de Saül s'enflamma contre Jonathan, et il lui dit: Fils pervers et rebelle, je sais bien que tu as pour ami le fils d'Isaï, à ta honte et à la honte de ta mère.