Formal/Neutral:
* Je t'aime, mais je ne peux plus supporter ça. (I love you, but I can't stand this anymore.) This is a direct translation and quite straightforward.
* Je t'aime, mais cela devient trop difficile pour moi. (I love you, but it's becoming too difficult for me.) This focuses on the difficulty of the situation.
More emotional/direct:
* Je t'aime, mais je n'en peux plus. (I love you, but I can't take it anymore.) This is a more passionate way to say it.
* Je t'aime, mais c'est fini. (I love you, but it's over.) This is more definitive and suggests a break.
Specific to the situation:
* Je t'aime, mais je ne peux plus vivre comme ça. (I love you, but I can't live like this anymore.) This implies the current situation is unbearable.
* Je t'aime, mais je dois partir. (I love you, but I need to leave.) This is more about the need to separate.
Adding more context would help me give you a more accurate and nuanced translation. For example, what is the "this" you're referring to? What are your feelings towards the other person?
Remember, the best translation will be the one that best expresses your emotions and the specific situation you are in.