<human>: Can you succinctly summarize the text in 1-3 sentences?

I'm 16, she's 16. This both of ours first relationships. We broke up 6 months in and I had a short relationship with someone else, we got back together afterwards and it's been 14 months since then. We both go to the same school and are within the same social circle. 

I've been wanting to break up with her for a while and communication between us at the moment is the lowest I think it's ever been. From what I can tell she's by far more heavily invested in this relationship than I am.

I want to break up with her as respectfully as possible and I'm open to remaining friends afterwards.

The thing is, she leaves for a family vacation this Saturday and I'm not sure if breaking up with her now would give her a whole vacation to get used to not being with me, or if it would come off as cowardly for not wanting to go through the awkwardness of post-breakup inter-social circle activity. 

I really do have her best interests in mind (in relation to having as tactful a break-up as possible), and I don't mind waiting for her to come back. She is most likely getting me a gift from overseas and I'd rather not have her become more invested in this relationship.

If I were to wait for until she gets back, how long should I wait until I break-up with her?
<bot>: Girlfriend of ~20 months leaves for holiday in 3 days and I'm not sure to break with her after or before her holiday.