That sounds like a healthy way to handle it. If one member of a couple that's just opening up is experiencing anxiety, it can be very affirming to have it demonstrated that their partner is willing to slow down, pass up opportunities for fun things like sex, and otherwise prioritize them and show them that they don't take second place just because they're no longer the "one and only" when it comes to certain things.
And good on you, R, for reading and taking in what was said even though it was rough, that takes some courage.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.