This comes up so much here, and I totally understand the fear behind it.
Short answer: No, it doesn’t ruin anything.
The soul connection exists regardless of what either of you does in the physical. Like the people you hear talking about ‘cord-cutting’ are just repeating buzzwords they heard.
I’ve seen twins reunite after one or both were married to other people for years. Plenty of people have either been dating someone else or met their twin when they were dating someone.
That’s actually pretty common for reasons we should talk about another time.
You also might want to see this thread, discussing whether you even can move on:
What I will say is there’s a difference between genuinely focusing on your own life and happiness vs. strategically “moving on” hoping it’ll make them come back.
The first one often does shift things energetically. The second one… your twin feels the difference even if you are able to lie to yourself about it for a while.
Dating a soulmate isn’t closing a door. Sometimes those relationships teach you exactly what you need before union is even possible.