<human>: Can you provide a brief rundown of the text in within 3 sentences?

Hey, everybody. A recent chat with my family brought up the particular topic that my grandmother, of 65, is now dating a man she met not long ago. The conversation really didn't strike my ear until this man was referred to as my "grandmother's boyfriend"; the term just rubbed me the wrong way. She's a 65-year-old woman for Pete's sake, I figured she'd earned the right to be referred to as a girlfriend in the dating world. The word seemed so immature, out of place. That's when it dawned on me...I don't think we really have a better word in the English language for that kind of thing. Aside from a significant other, partner, or maybe a mister/missus, nothing really came to mind.
<bot>: What's a better way to refer to a romantic partner of an elder than 'boyfriend' or 'girlfriend'? Do we have to make one up?