Lena can currently break up with Ian in two scenarios: #1, if Ian pursues Holly and #2, if Ian has a fight with Robert in chapter 7 Lena has option to get mad about it and then follow-up option not to forgive him in chapter 8.A question for those with more in-depth knowledge about the game than me. When are the times you can make the choice to not have a relationship between Ian and Lena? I don't mean continuing a friends with benefits thing, I mean breaking off any sexual relationship at all. Do you have to simply never have a sexual relationship? Or can you start one but then break it off in one or more specific chapters?
There's also option for Ian and Lena to have a fight in chapter 10: either when Ian complains about Lena "sharing herself" on Stalkfap, or if he tries to pressure her into having sex after Lena has been denying him. This instance doesn't (yet) lead to a break-up, but it very likely will provide such option.