These are common acronyms that can be used on social media or over texting. Sometimes they are separated or together. Nonetheless, at their full value, they mean:

Thank you so much I love you so much (tysm ilysm)
You're very welcome I love you so much, too (yvw ilysm2)

These can be used to show how much you love someone and your absolute gratitude. In return, you can show how much you appreciate the person's love by saying at back and acknowledging their thankfulness.
Example of a texting conversation where tysm ilysm/yvw ilysm2 are used:

Person A: You look stunning today!
Person B: TYSM ILYSM!
Person A: YVW ILYSM2
Person A: YAS!
Person B: <3
by LingDanc803 July 10, 2018
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