Dragon Age 2 - How not to lose Isabella?

I'm playing dragon age 2 and i've already got Isabella on my team and romanced her too. Now i'm doing to catch a thief. I did it but there is a letter saying she is leaving. Is she going to come back ever? If not what should i do so she doesn't leave because i saved the game before i did the quest. I know she can leave like 3 times during the ending of act 2 what choices should i make so she doesn't leave can anyone tell me please?|||As long as you had her friendship above 50% and you did a mission where you talked to her at the Hanged Man during Act 2 (called her mid-stage relationship quest), she should return to you during the end of Act 2.