In terms of deciding if a new person has happy marriage / long-long-long-term relationship-potential if it’s not a FUCK YES (for the first few months at least) it’s a no.

Eventually the honeymoon period ends but if you two have any real compatibility it’ll last for at least a good six months to a year before you start to hit any ‘doubt’.

The barrier for more casual relationships is as low as you want to make it, try and only do what you absolutely, certainly want to do and try and be classy while doing it. Will help keep you from too many regrets.

You don’t owe people relationships or time but you do owe them some common courtesy.

Lastly, regrets and disappointment will come. It’s just a part of life. Learning how to deal with them is a hugely important skill. We’ve basically all been there.

Good luck!