There are so many things going on here. You're worried about the possibility of a relationship "breaking down without physical distance, especially at the start", yet you are engaged. Oh, you just got engaged in Feb. after knowing each other for 4 months. I see.
You spent a month away from your partner (fiance), and that caused lots of problems. I see.
This engagement has problem written all over it, and the fact that you've rushed into a relationship that can't withstand public health and safety measures is really a you problem; please don't make it an us problem by blaming it on social distancing measures.