[!Yaminashi]

You mention that he keeps saying you're the only one that he loves but his actions speak louder than words. Are you saying you're getting feelings of him being unfaithful or did you just word that poorly?

Has he told you before that he WANTS to marry you or have you guys just talked about the IDEA of marriage?

Sit down with him and have one last talk before you make your decision, and really try to reiterate that you're doubting his intentions; especially after 10 years together.

I don't feel that you're being unreasonable but I would sit down and have a really serious talk, not just a discussion. The last thing you want to do is force him into a situation he isn't ready for/honestly willing to commit to, hence why the ultimatum route is a bad idea.

I think at a time like this, you need to start worrying about yourself and your life. I know relationships are all about tackling life together and being there for each other but if your end goal is to get married and this guy doesn't want the same you should definitely get out.