Well, it all depends on which guy, doesn't it? She likes Yutaka (even if she hasn't explicitly admitted it to herself yet), so him putting a bandaid on her makes her blush, and him sniffing her ear makes her blush a lot.
She doesn't give a single shit about Senga (this has been made explicit repeatedly), so him sucking on her neck is no problem and not embarrassing at all.
I just reread chapters 1-8 (getting ready for 9) and didn't find a single thing inconsistent as long as you can comprehend that women (and men) react to the same things differently depending on who is doing it.
I am frankly boggled at all the people who think she should be reacting to Senga the same way she reacts to Yutaka or it's a 'disgusting trick'. She is not your typical 'ho harem heroine (who acts nothing like an actual woman). Senga is a worm to her, it doesn't matter what he does (up to a point which has not been crossed). If you think this is weird (or 'disgusting', lol), that's entirely your fault.
If you still have trouble understanding this, imagine getting a kiss from your [hottest 2d or 3d woman of 2023] vs getting a kiss from TS Vladamir Pooty Poot. You might react differently. If you'd get more of a boner from TS Vladamir Pooty Poot I'd at least understand that's consistent.