I think sabrina will come back and if not you should stay with Lena and Jake cause they seem pretty chilled, I understand that it hurts to think that you potentially lost the love of your life but on the other hand if you will ever meet someone similar than you could just make thinks clear and start with telling the truth about lena jake and you. If she understands it and has no Problem with it them thats the girl for you.

Best solution would be if you agree on like a other name with your gf something she alrdy calls you like babe or so , but it should be okay to usw in public.

I for example dont call my gf by her name so even if she would change her name, it wouldnt matter for us.

If you feel like you can talk to her about everything then talk about your feelings dont set her under pressure but be honest maybe she feels the same and you could plan the future somehow together :)