Hello louisaninja. I am sure that can be quite frustrating for your text messages not to go through. Does this issue occur with everyone you text or just your boyfriend? Do you text other Sprint users? Do the messages go through? Is he having issues with text messages? Please answer these questions so that I can better assist you.
Follow me on Twitter @VZWSupport
I'm actually dealing with this same issue--boyfriend's got Sprint and I'm not receiving about 1-in-3 of his texts (along with a couple texts from some others using Sprint.) One night a couple weeks ago my phone received all of them (about 25 from him and 5 from others), but the issue started up again about a week later. They're receiving all the messages I've sent, and none of them are having issues with messaging other people (either receiving or sending).
I seriously hope to hear back on this soon and have this issue solved! Thanks!