Responsive means never fixing a widow
If you’re designing a responsive piece (website, email, etc) and you’re trying to design it so that a particular line of text sits nicely on one line, you are doing digital wrong. If you are not letting text flow and wrap naturally, you are designing wrong. Different devices/browsers/platforms will display text at different sizes, and different screen sizes will cause different wrapping of text to occur. We have to embrace this, not resist it. Trying to control line breaks and text wrapping across platforms is a losing battle. Not only is it a battle we shouldn’t be fighting; it’s a battle that has no place in the whole conversation about digital. It goes against the philosophy of digital media and the nature of responsive design. If you’re even talking about trying to control line breaks, widows, etc, you’re doing digital wrong. Period.