Here are my suggestions to hopefully head something like this off in the future.
1. If you want to get married and be his forever you have to let it be known soon on in the relationship. Otherwise if he is taking you for a ride you are a willing rider (this is not referring to abusive situations, just misunderstood ones).
2. Don't move in with him (her) unless you are married. That will prevent a whole lot of misunderstandings.
3. Give him/her a time line and stick to it.
4. Don't assume that there are plenty of others to choose from because sometimes there aren't. But you will still be better off alone than with a loser and/or creep. mg