The female lead was the fiancée or wife of the male lead, but in the novel she read or the past life he loves other woman or is destined to be with the OGFl, so she is like “let’s be friends and divorce when you fall in love with her” but instead he becomes obsessed with her, and after coming back from war , he still loves her, oh, and the knights wants the male lead to marry the other girl whom he met in the war since they think that the female lead doesn’t love him since she didn’t send him any letters when he was in war (she send him but someone didn’t deliver them to him). Also, i don’t know if I’m confusing this part with other similar manhwa who i also don’t remember the name, but the male lead was a child and cried when he realised he has to go to war and leave the female lead.