How long have you been with your BF? Anyway, I'm sorry that you are in this situation. It seems to me that him going back (where ever back is) to handle his business with his children should NOT code for ending his relationship with you. If you gut is telling you it is, I would strongly consider concluding things as harsh as that might sound. Either way, you need to protect yourself and this is what I would do.:
- Reach out to him and show your support for him and his children.
- Ask if there is anything you can do to help him.
- Ask him how long he needs to be away (to fix things with his children approximately).
Showing support towards him and his children, lets him know that you are an ally in this situation and not apart of his "problems". Lastly, by asking him how long he needs, that should give you some information to ease the emotional uncertainty that you may be feeling with his need to fix the children situation first before you guys.
I hope that makes sense.