About me: TRP for 4 years, own local business, lifting 4/week.

Plate of 3 months told me last night she likes me and want something serious, I played it cool and question disappeared. Tonight she messaged me saying she wanna talk seriously with me, I know she will tell me she want to be exclusive or in relationships. I only want to have fun with her but dont wanna lose a plate. I have 2 girls rotation at this moment and very busy with work so losing her would be a minor loss but unpleasant.

How to be in this situation?