Tips for healthy relationships?

Hi ladies so I'm just looking for tips and advices to be in a healthy relationship. I'm 21 still young and learning to be the best version of myself. I am currently single and happy with myself but from the past two relationships I've had, I notice a pattern.

Somehow my self confidence deteriorates once I get into a relationship and all that self love I've built up when I was single comes to a halt, if that makes sense.

This usually ends up with me being dependent on them or I lose sense of myself. I'm not as independent or happy as I am now. Must I say I was cheated on both times, but I'm all over it now and never felt better about myself.

The only thing left is I'm worried about getting into a relationship. I am not looking for one at the moment as I am content, but I want to ask you more experienced ladies for advices for when I do meet a special someone in the future. How to not fall into old habits of unhealthy relationships and still feel as good as when I am single?