Beth, a key character in the TV show Yellowstone, is not shown to have disclosed the reason for her infertility to her partner, Rip. There could be a number of reasons for her decision to keep this information to herself.

One possible explanation is that Beth may feel uncomfortable discussing her infertility with Rip. Infertility can be a sensitive issue and may be difficult to talk about with one’s partner. Beth may feel embarrassed or ashamed about her inability to conceive and may be concerned about how Rip would react if she were to share this information.
Another possibility is that Beth may be afraid of Rip’s reaction. As a tough and occasionally violent character, she may be concerned that he would blame her for their inability to have children, become angry or distant, or even end their relationship.
It is also conceivable that Beth has not told Rip about her infertility because she does not want to burden him with this information. Rip is a devoted partner who is busy with his work on the ranch and his ongoing battles with the Dutton family’s adversaries. Beth may feel that he already has enough on his plate, and she may not want to add to his stress by revealing her own struggles.
Alternatively, it is possible that Beth has already told Rip about her infertility in an off-screen conversation. The show often omits certain conversations or events and leaves them to the viewers’ interpretation. It is feasible that Beth and Rip have already addressed the issue and have come up with a way to move forward as a couple despite their inability to have children.
In summary, it is not clear whether Beth has informed Rip about her infertility, and there are many explanations for why she may have chosen not to. The show leaves this part of their relationship open to interpretation, and it is up to the viewers to form their own conclusions.