Stealing? No, its repayment.

Hypothetically, if you have made agreements, verbal and written with a person you love and care about, and that relationship ends, do all agreements made while in the relationship cease?
First Part...
You register and insure their car, because they couldn't afford to themselves. An Agreement is made with an understanding that any photo radar tickets will be paid by the driver of the vehicle (not the registered owner), and only a licensed driver would drive the car, the person can use the vehicle as normal. Now, say the relationship between the 2 people ends, with a month left on the registration/insurance, and a $250 ticket yet to be paid, the insurer asks to have the plate returned, and gives the paperwork to the other to absolve any future liability. The agreement that tickets obtained while registered by you for them will be paid didn't just stop. The plate does not get returned, and they just assumed they could continue to use it until the registration end date. They promise over and over to pay you back for the money owed ASAP. 2 months later no attempt to make payment.

Second part, to make this a morally interesting story, goes like this...

You and they, have been in a decent relationship, they have used your computer, they have given you their bank card with pin to do transactions for them more than once. The relationship ends, and you assume, "Whats good for the goose, is good for the gander". On your computer you see their banking access has been saved, card number and password. They owe you $250, and have told you when they get paid, they will pay you. You sign in to their account, like you have been allowed to in the past, more than once, and see that they have been paid twice since promising you payment. You then etransfer the $250 and no more from their account to your account, you erase your account from their payee list, sign out and erase any banking info that was saved on the computer. The money transferred was not the last in the account, it left around $1000 in the account.

So who is the thief? Is one person morally better than the other? Are the assumptions made equivalent? Should 3rd parties been involved and paid, to delay and find fault?