Of course! Here’s a message you might consider sending to your boyfriend:
Hey [His Name],
I hope you're doing well. I’ve taken some time to reflect on my decision to end things, and I want to reach out and express how sorry I am for how everything unfolded. It was never easy for me, and I realize now that my choice might have hurt you deeply.
I’ve thought a lot about the good times we shared, and I genuinely regret the pain my actions caused you. You deserve kindness and honesty, and I wish I had handled things differently. I'm really sorry for any pain my decision brought you.
I understand if you need space or time, but if you’re open to it, I’d love the chance to talk things over. Regardless of where we go from here, I truly wish you all the best.
Take care,
[Your Name]
Feel free to modify it to reflect your feelings and the specifics of your situation!