You said that Ian is thinking about them the way he did S1-3, so do you think Ian's bipolar disorder changed the way he thought/viewed their relationship during season 4 and 5?
This is... really complicated... and I think I rambled fairly far off-topic at some point here, but I REALLY don’t want to edit:
I haven’t actually drawn a parallel between S1-3 and S7 properly, before...
But in S1-3 (and to an extent into S4), Ian was chasing that One Big Romance. He wanted the guy and the future and everything else that came along with it.
In S4, Ian was clearly (in retrospect) manic, but he was also really starting to have Mickey in the ways that he wanted to.
And then in S5, especially the first half of that season, Ian and Mickey HAVE that family life that Ian was thinking about in S1-3 (and that he was talking about again in 10x03). So, it’s a lot more about the here-and-now, rather than saving those goals for the future.
So, on the one hand - yes, Ian’s mania in S4 and S5 kind of interfered with Ian’s Grand Ambitions for his relationships...
But on the other hand, was it the mania, or was it just that Ian didn’t NEED to consider the future? He already had the guy and the kid and the family life.
And the thing is - I know that a LOT of Shameless fans have always tacitly agreed that Ian wanted that settled family life. I know this because there is a disproportionate number of fics, written and set in times from S4 to the mid-2030s, about Ian and Mickey and Svetlana and Yevgeny (and the Gallaghers and Mandy and Iggy and Nika, from time to time) as a family unit.
And then you look to S7-10. S6 gave us a hard reset on the Gallavich front. They were broken up, Svetlana married V, and Ian had completely lost his status as a parent to Yevgeny. When Mickey returns in S7, in a lot of ways it’s a reset to how they were in the earlier seasons. I don’t have any solid examples, but it does seem to me like Ian was once again thinking about the future when he ran away with Mickey, before realising that maybe he CAN’T have the future he wants if he stays with Mickey.
Which brings us to S9 and 10. I think this is really a continuation of the S7 story. Mickey’s back, but there’s still no Yevgeny or Svetlana on the scene. They’re back to their S1-3 status quo, in that regard, so it’s natural that Ian is thinking about the “next time” they can bring back those traditional hallmarks of a relationship together.
In summary: I think it’s not that Ian changed the way he was thinking about their relationship, necessarily. I think it’s just that as the relationship changed, the things he used to think about were just... happening, so there was no need for further-flung goals on that front, until they came crashing down again in S5-6.