We appreciate the sensitive nature of this question.
Dyspareunia is an increasingly common diagnosis, with great ramifications for a couple. (On a medical note, use of hormonal contraceptives is sometimes associated with increased vaginal dryness and with lowered libido.)
Our site’s rabbinic supervisor, Rav Yehuda Henkin permits ejaculation at the very entrance of the vagina, without penetration, in these cases. Out of concern for hotza’at zera levatalah, he would not permit freely ejaculating outside without more detailed information about the specifics of your wife’s condition.
It is a testament to your strengths as a couple that you have found a path to satisfying and enjoyable intimacy notwithstanding her condition. While we agree that it is your wife who is most directly affected by it and who must make choices about her health, we do not view a desire on your part for her to seek treatment as essentially selfish. Her condition has a direct impact on you and limits both of your options for intimacy, as well as affecting choices about conception and contraception.
Although there is a substantial investment in time and money involved in seeking treatment, the dividends can be well worth it for both of you, especially when considered in the long term. Many women with dyspareunia feel discomfort, embarrassment, or fear which can be exacerbated by the prospect of seeking treatment. We suspect that these also play a role in your wife’s reluctance to pursue physical therapy.
As far as broaching the matter, we suggest choosing a time carefully (or even asking in advance for a good time to really talk) and beginning by asking your wife how she feels about your intimate life, with a focus on drawing her out and listening to her. What does she enjoy more or enjoy less? How can you increase her satisfaction? How does she see her condition as affecting your relations? How can you be most sensitive to it? See if you can follow up concretely on what you learn.
In a follow up conversation, you can ask if she’d be open to hearing about how you feel. Be sure to share all the positives, and then tell her about the halachic considerations that have been weighing on you and about any desires you might have for more options for intimacy.
Then follow up by asking her if she’d be willing to discuss pursuing treatment. Ask her what her feelings about it are, tell her in a loving way why her pursuing it would be meaningful to you, and lay out steps you personally are willing to take to support her treatment (whether by helping her reach her appointments or pitching in extra when she needs to go).
We hope this helps. Please let us know if we can be of further assistance.