Based on recent previous case, yes, they don't mind you having another account as long as you doesn't use it for malicious intent like bonus abuse or circumventing limitation. I took a quick stroll on their ToS and couldn't find anything about prohibiting second account.
But... that fact become rather useless because the case involves a self-exclusion. Self-exclusion works by locking into several datapoint. IP address is one of it. Given OP [if we amuse a possibility that he's telling the truth] shared the same IP with his husband, whom self-exclude himself, and add the similarities of email address, Rollbit's step to block the account is already correct and correspond with the Gamble Aware regulation.
I guess this is why their support said that you are trying to escape the ban. Now that makes sense. I don't know why people use the same IP address to gamble, especially when they know that their partner is self-excluded from the same platform. If the case is true, which OP already said that their partner has an account there, I don't think we should blame Rollbit for that.
Usually, exchanges try to find mistakes from players, and casinos do not disclose the reason they banned an account. In this case, the user already agrees that her partner was playing in the same casino and the case is clear to understand.