Sore jaw tips needed ladies!

So my wife and I love to please each other before intercourse, but we have a small problem. She can't keep her mouth open for very long because it hurts her jaw. She likes to perform oral on me and wants to make me go, but can't do it long enough and feels bad afterwards even though I reassure her that I don't mind at all and that I love her very much. Still, if we can get it to happen I think it would definitely improve our sex life. We aren't struggling sexually by any means, but I'm worried it could be a self esteem issue later. Please help ladies (and gents)! Thank you!